magic-itemspathfinder-1e
Looking over the items I'm going to want for my character, I find myself wanting two neck slot items (an Amulet of Mighty Fists and a Necklace of Ki Serenity).
The Hand of Glory allows a character to wear an extra ring by taking up third neck slot, are there any other items that exchange what slot can be used where? (Hopefully one to let me wear more than one necklace at a time?)
You actually have two questions here, which should probably be turned into two questions on the site. I'll answer the first one, and come back later for the second.
Q. You want full body armor via magic, and you want it to last until next sunrise.
2 shifts of power equals 1 armor rating increase, plus 1 shift for a duration of a day.
As so frequently happens in FATE, there is more than one way to do this.
Answer 1. Straight up thaumaturgy can do this. 2 shifts of power get us a one shift armor rating. That's a good starting point. By default, a thaumaturgy spell lasts until sunrise/sunset, so lets thrown in an extra shift to make sure we have the whole day. Armor is rated on a scale from 1 to 4, though it can go above that if we really want to push it. Assuming you have Lore 5, the obvious setup is Armor: 2. (4 shifts for the armor, +1 for duration, for a complexity of 5.) If for some reason you really think you're going to take a pounding, a pair of aspects will get you Armor: 4 (8 shifts for the armor, +1 for duration, for a complexity of 9.) Given that Armor: 4 will stop military ordinance and explosives, that should be sufficient. That would take two aspects however, so I'm not sure you could keep that running constantly. (If you have less lore than I guessed, by all means adjust downward or grab more aspects.)
You specified complexity 8, which is a little tricky. See, Complexity 8 will get you Armor: 4, but without that spare point for duration, so it will fade at either the next sunrise or the next sunset. That said, for a few hours, you'll have Armor: 4. An important note- this armor will only apply against one kind of stress. I would guess you're planning to apply this to Physical stress, and it's exactly the same setup for Social and Mental stress, but just be aware a smart foe will start hammering on you socially if they notice how you're armored.
This is a great setup for a mage who wants some protection, and is done using nothing but the normal thaumaturgy rules. However, it only gives you armor, and stacking more cool things on it is going to increase complexity in a way that might be troublesome. You can certainly make it better with more aspects to tag and more time to set it up (I'm ignoring the actual channeling of the magic here, assuming that you channel 1 shift of power each round, and control it easily. If for some reason you do not have the time to do this, best of luck, and !) but that makes it hard to keep on hand. That said, if you have the time and the aspects, 21 shifts of power will buy you Armor: 10, a number that makes me giggle like a schoolgirl and will render you practically untouchable in a conventional fight. If you want armor from magic, this is how you do it. If you want the full Ironman power set, I'd look at option 2.
Answer 2. Pretend it's magic, but system-wise it's a power. If you don't plan on using Thaumaturgy in general, and just want to be Ironman, this may be a good fit for you. Supernatural Toughness will get you Armor: 2, plus extra stress. It's -4 refresh, but you can buy that down with a good catch. (For Ironman? EMP seems like a good choice, but that's depending on how you skin your magic.) I would actually give yourself the Human Form/Beast change powers if you're going this route- That lets you stack cool powers onto the suit, offsets some of the cost of it, and is a good analogy of you in suit being better than you not in suit. (As a side benefit, that lets you shuffle your skills around between suit and not-suit, which may be to your liking.) Breath Weapon (-2) and Wings (-1) both look good for this too- Representing energy blasts and jet packs. If you just want the armor, this will be -4 refresh +X for whatever catch you come up with. If you want Breath Weapon and Wings, it will be -7 +X for the catch. (-4 for Toughness, +X for the catch, -1 for Beast Change, +1 for Human Form, -2 for Breath Weapon, -1 for Wings.)
This is the best setup for the actual Ironman, as it leaves the possibility of getting caught out of the suit from time to time and gives you some of the other cool things he can do. It's refresh intensive, so you may not want to take actual thaumaturgy with this, so it's not that great of an answer to the original question, though it may be a better answer for the intent.
The following let the barbarian actually rage using his own kind of rage more often than normal. "Whirling frenzy is otherwise identical to the standard barbarian rage" (UA 66), so these should work with that, too.
The 2nd-level Drd spell blood frenzy [trans] (Spell Compendium 33) causes 1 touched creature to rage as if it used its special ability rage normally "but this rage does not count toward the creature’s number of rage attempts per day." Note: Rage attempts?
This is likely the best choice, equipping an ally with a wand of blood frenzy (2nd-level spell at caster level 3) (90 gp/charge) and the barbarian himself with a potion of blood frenzy (2nd-level spell at caster level 3) (300 gp; 0 lbs.) in a potion bracer (Sharn: City of Towers 158, 159) (100 gp; 1.5 lbs.) for emergencies (that is, if the DM's not ready for the ready-drink helm to enter her campaign.)
The shoulders slot item mantle of rage ("New Magic Items" 2) (6,000 gp; 1 lb.) grants the wearer, if a barbarian, the ability to rage 1 additional time per day, and, if not a barbarian, the ability 1/day to rage like a level 1 barbarian.
In addition to the 3rd-level Sor/Wiz spell rage [ench] (PH 268) et al. (which isn't really rage but a buff spell with attached penalties), there are a few lesser alternative sources of barbarian rage not involving taking levels or feats.
Yes, that last scrapes the barrel's bottom.
Best Answer
There are a few magic items that will use a slot different than normal, to name a few:
But no, there are no magic items that will grant you an extra neck slot.
Non-humanoid creatures have access to the Extra Item Slot feat, that grants an additional magic item slot. But this would only help you if you had no neck slot, since the feat can only grant you a slot that you don't have already.
Another option would be to use a Magical Tattoo, which can be also placed on your neck but does not take up your neck slot. Or even take a look on the available Ioun Stones to check if the effect you want is not already covered by one of them.
Considering you are trying to obtain extra ki using the Necklace of Ki Serenity, you should take a look at the Ring of Ki Mastery, which allows you to store up to 2 ki points for later use and reduces the ki points used by ki abilities.