I've recently been playing a Way of the Kensei monk (from Xanathar's Guide to Everything), and am currently level four. While I like the subclass and most of its mechanics, it disappoints me a bit with how those mechanics effect its flavor.

I'm supposed to be a specialized expert in fighting with my chosen kensei weapons, but in practice I seldom use them for my attacks, instead mostly attacking with unarmed strikes, and only throwing in a weapon attack occasionally (such as for opportunity attacks). Even when I get the Extra Attack feature in another level, I expect I'll usually just make one weapon attack per round, while often making two or three unarmed strikes.

There are two reasons for the prevalence of unarmed strikes:

1. The Martial Arts and Flurry of Blows monk class features that let me make attacks with a bonus action only allow unarmed strikes.
2. During my Attack action, I often want to make an unarmed strike in order to activate the Agile Parry Kensei feature (giving me a +2 to AC until my next turn while I'm holding a kensei melee weapon, but only if I make at least one unarmed strike with my Attack action).

I'm contemplating homebrewing an additional mostly-flavor class feature for the Kensei subclass. Before I discus it with my DM, I wanted to assess its balance relative to the normal Kensei (and other Monks). I don't really want or need a power boost, I just want a way to reflavor my existing powers.

Here's my proposed subclass feature (available immediately after adopting the subclass at level 3):

An extension of the body

Whenever you could make an unarmed strike, you may instead make a special melee attack with a kensei melee weapon you are holding. This special attack must use your Martial Arts die for damage, even if the weapon could normally use a larger damage die. This special attack counts as an unarmed strike for the purposes of other Monk class features.

The idea is to reflavor the unarmed strikes I'm currently making as underpowered attacks with my kensei weapon, without changing my damage output. With the new feature, all my attacks could be made with my weapon, even when using Flurry of Blows or Martial Arts. It would also let me qualify for Agile Parry without skipping weapon attacks on my Attack action. I can still make normal weapon attacks, they just won't count as unarmed strikes unless I forgo the weapon's better damage die.

Known balance issues with the proposed feature:

• This feature may let a Kensei change the type of a lot of their damage from bludgeoning to piercing or slashing (depending on what kinds of kensei weapons they choose). This probably doesn't matter much, as according to the answers to this question only a relatively small number of creatures in the Monster Manual have resistances or immunities to specific kinds of physical damage (rather than to all three types), and among the physical damage types, bludgeoning is probably the best. But having extra options is probably a small benefit.
• The feature would also make using a magic weapon quite a bit better, as you'd gain whatever magical benefits the weapon offers on every attack without giving up the use of any class features. For example, my DM has given my character a magical spear that does extra damage on a critical hit, and I'd get a lot more chances at rolling one with this homebrew than I do using RAW. But note that it's mostly just the magical effects of the weapon that matter, not so much its being magical for overcoming damage resistances, since a Kensei's unarmed strikes and kensei weapon attacks will all count as magical at level 6 anyway. The new feature would however give more benefits from the Sharpening the Blade Kensei feature after level 11 if your weapon doesn't have a magical attack and damage modifier already at that point.
• Some possible kensei weapons have special properties that you can't normally replicate with unarmed strikes (such as reach from a whip, or silver plating to bypass certain damage resistances). This rule would let those special properties be used for more attacks each turn.

My questions:

1. Are there any loopholes, ambiguities or other issues in the wording of the class feature?
2. Is the modified subclass still reasonably balanced relative to other Monks in terms of combat effectiveness? I'm not sure how to judge how important the balance issues that I've identified are. Have I overlooked any other important advantages this homebrewed feature would provide?
3. Would giving up any of the standard Kensei (or Monk) class features bring the balance back into line? For example, we could pretty easily drop Magical Kensei Weapons, as the Ki-Empowered Strikes feature would make counts-as-unarmed kensei weapon attacks also count-as-magical (at the cost of a little bit of damage for some kinds of weapons at lower levels). A more extreme trade-off would be taking away some or all of the improved damage that Martial Arts gives to unarmed strikes (so you'd need to make weapon attacks instead, and would be quite a lot weaker without access to a weapon).