This answer is going to come off as extremely negative. Unfortunately that is my best analysis of the class. So before I get into I want to say; I love the theme of what you were going for. A patron that could be a level 20 character from a previous campaign is great. I also don't want to discourage you from homebrewing stuff in general, this class has a lot of issues though and I felt it was necessary to point them out.
This is unbalanced and breaks the style of warlock patrons
This patron makes such a departure from the typical structure of a warlock patron that it is somewhat difficult to assess in balance terms. My gut says it is very over-powered and I will try to go through each feature to explain why. Note; this analysis is focused on comparing it to other patrons not the entire warlock class.
Expanded Spell List
A standard feature of warlock patrons that you have re-interpreted, both in good and bad ways. Overall your version is overpowered and needs to be fixed.
Spell List As Spells Known
The PHB patrons get access to 2 spells of each level from 1st to 5th. They are simply added to the spell list and do not add to spells known. The celestial and hexblade patrons from XGtE only get access to 1 spell of each level but they still do not count as known spells.
Expanding the spells known of the warlock is completely against the design of all other patrons. This part of the feature is completely broken and needs to be removed.
@illustro points out that as worded this does not add additional spells known but instead forces the warlock to learn those spells. If this is the case then this feature is actually extremely weak, far worse than any of the other patron spell list options.
Choice of spell list
The choice of three different lists based on the spellcasting class of the patron is a cool thematic choice. However all three lists contain spells that are already available to the base warlock. The warlock list is worse than useless, while major image from the wizard list and banishment from the sorcerer list are already available to warlocks.
I would like to see this feature remain but it needs work on the spells chosen. I would drop the warlock list and a add bard, and/or druid list instead.
Lesser Mystic Arcanum
Nope. This feature is entirely broken. At 9th level your warlock has an additional 5 spell slots per day above and beyond their typical 3 per short rest. Not all warlock spells benefit from up-casting and having them in lower level slots does not sufficiently reduce their power. Giving this many additional spells is way, way stronger than anything any of the other patrons give at this level or at any level.
There is no point even comparing this to the other patrons in detail. In summary it is very overpowered and needs to be removed entirely.
Strategic Spell
This one isn't too bad. Rogues and monks already have access to this feature. However it does go against the normal style of the warlock. Apart from the celestial patron every other patron grants a once per short rest ability not an always on feature. By not being limited to pact slots this feature works on cantrips and is therefore infinite.
To answer your follow up questions, removing Dash makes no real difference, Disengage and Dash are about equal. And no; you absolutely should not include Dodge. Dodge is way stronger than either of the others, there is a reason rogue's cunning action does not include it.
This feature is likely a little overpowered due to unlimited uses, but only when compared to the other warlock patrons. Overall this feature is not game-breaking given you should be at range anyway.
Eldritch Weave
At first this one seems ok, but it is likely overpowered. Gaining temporary hitpoints is very similar to the Celestial Resistance feature of that patron, though that one allows you to also protect other creatures.
The issue with this feature is the additional feature: "your concentration cannot be broken until you lose all of these temporary hit points". This is extremely strong. Spellcasters typically take entire feats (War Caster, Resilient (Con)) just to buff their concentration checks. Your feature is negating them entire for a minute.
Yes, this benefit ends early if you get hit enough. But, at a minimum of 20HP and increasing every level this will take a few rounds. Assuming you are concentrating on some disabling spell like hold person or similar it might be impossible for the enemy to deal enough damage to break this before your party takes out your target.
This feature is overpowered and should be changed.
Greater Mystic Arcanum
If the early version of this feature wasn't so utterly unbalanced this would almost be fine. However; it isn't, and neither is this. At will hex at 14th level, then suggestion at 18th level is very powerful.
In fact this feature is exactly eqivilent to the 18th level Spell Mastery feature of the wizard, barring some flexibility. No other patron gets a feature anything like this. Several only get a single once per long rest ability.
At will casting of leveled spells is normally restricted to Eldritch Invocations. Allowing it in addition to those completely breaks the style and design of the Warlock. This is utterly unbalanced and needs to be removed.
Conclusion
Scrap the whole thing. The features are almost all overpowered and don't suit the style of the Warlock at all. Any one of the features (bar Strategic Spell) would be enough to make this class overpowered. Added together this is completely busted.
You are adding flexibility by increasing spells known with your 1st level features, and you are increasing overall power level by giving out way more spell slots. This Warlock is so much better than the others there is almost no reason to look at them unless you want to be a melee fighter.
Back to the drawing board for this one.
No. A few things to note that stand out
crafting bonuses at lv. 3. Being able to gain the equivalent of a current lv 10 ability for artificers at lv 3, even if only for one kind of object is overpowered. Being able to gain powerful armor so early in the game seems cool, and is, but it is way too powerful at such a low level.
too flexible. With all these available options at lv 5 and increasing, this gains too much flexibility for a subclass. Consider that one of the main properties of the warlock is the eldritch invocation, and that you have a similar amount of special abilities as invocations for the entire class, as one of the class's main features, and you can see that for a sublcass, this is way too good.
Lackluster higher abilities. I get that heavily armored is supposed to be it's main thing, and it's scaling is most of the subclass, but the higher abilities are so underwhelming that they almost might as well not exist. The sixth level thing is confusing, and better suited as part of the original ability, and martial weapon proficiency at lv 14? I don't want to harp too much, but that is way too late to be gaining proficiencies in weapon types. At that point your character should know what weapons they want to be using, not gaining proficiencies in all martial weapons.
Inbalances in the main feature. The main feature, as mentioned previously, is obviously the Heavily Armored ability. At level 17 you can use the majority of your subclass' ability into casting a cantrip as a bonus action, while at the same time at lv 12 you have protection from most mind manipulation, and at just lv 8 you can essentially be the ultimate underwater explorer. These are quite large differences, and the problem is that in the quest for diversity in options while retaining balance, most of these abilities come across as bland, and not particularly diverse at all.
Confusion with the main ability. The AP points don't make much sense to me. You start out by saying you spend them to enchant the armor, but then all the later abilities require using them (and not a small amount of them), but only at later points in time. You need to clarify if you need to save points, or if you can unenchant things later or what. Also, either way, the limit on how many you have versus how many you spend on later abilities makes them quite limited, when you generally just want to have cool enchanted armor
It's not all bad. I do like where you are going with this though, regardless of what I have just pointed out, and I don't want to feel like all I'm doing is shutting you down here. I'm not. I really like the idea. I really like the basis behind the main ability. I love the idea of an armor-enchanter. It just still needs work
All and all, I really like where these ideas are coming from, but it needs a lot of work. By trying to create diversity while retaining balance you seem to have achieved neither. So here's my advice.
Move the armor creation ability back. It's just too powerful for a lv 3 character to have
Move up martial weapon proficiency. At lv 14, people either have martial weapon proficiency, or they don't. And if they don't they've already built around that, so essentially the proficiency at this point is pointless.
Consolidate the armor enchantments. Instead of having so many different enchantments that don't get any job done that they are supposed to, make a few packages that get better as you level up. Like this:
Mind Protector (Requires 10 AP): You gain immunity against mind controlling effects created by spells of level 3 or lower. For every extra 2 AP spent on this enchantment, the spell level it protects against increases by 1.
Have a few sets like this, and you can have diversity, utility, and balance all in one, without being too much or too little of any.
Change the other AP abilities. The other AP abilities are just confusing with how AP works. Instead make them into enchantment sets of their own, or build them into every set, as I describe next
After this, you might need some more abilities. Not to worry. A good way to do this could be to have the abilities of each enchantment set get an enhancement. Perhaps have an ability added to each, that lets you de-level them in exchange for a temporary boost. Something like that. Or, create new abilities that just give all of your enchanted armor some bonuses. That would work as well
I really hope that all of this helps you. I can't wait to see how you change this for it's next version, and I hope that this helps gives you a feel for what needs changing in that next version.
Best Answer
Most of this looks fine, so I'll mainly focus on the outliers.
And boy-oh-boy is the level 18 ability an outlier. That said, I do want to preface this by saying that stepping outside the bounds of balance is the best part of homebrew. This criticism shouldn't distract from the fact that you've got a fun subclass on your hands; it just needs a bit of tweaking.
Umbral Incarnate is significantly more powerful than any other Sorcerer option, and probably any other ability in 5e.
I would be scared to put this ability on a BBEG, let alone a PC. As it stands, it will warp player choices across classes while simultaneously resulting in an unsatisfying gameplay pattern. Let's start from the top.
Overall, there's just way too much stuff in this ability, but it's not a bad idea. Tone it down and you have a cool kit-amplification ability.
6th Level has too much packed into it.
Either abilities are fine on their own, but I strongly prefer keeping Umbra Tentacle over Far Touch:
Umbra Tentacle is a neat, gameplay defining tool, as it:
I would clean up the verbiage to make it the source of the ability more clear (does it come from you or a point of your choosing?), but on its own I think this ability is a solid foundation to build upon.
Far Touch, however, takes this ability over the top. Umbra Tentacle is similar in power to each other 6th Level ability, so there's no need to cram another ability in, especially something as powerful as a cost-free Distant Spell usage on every touch spell.
Far Touch should be moved to 14th Level. Into the Void can go.
As the ability to see through magical darkness is an integral part of this subclass, in most cases the Sorcerer will want to engage enemies from the cover of magical darkness. As such, attacks against them will already be made at disadvantage, so Into the Void will rarely be useful.
Good news: this is the perfect spot for Far Touch.
1st Level is great!
1st Level is thematically satisfying and directs the Sorcerer into choices that will reinforce the thematic of this subclass. No tweaks needed here.