While I definitely agree that we should try to port all PvE guns and tools to PvP, the armor kit would need extremely careful balancing. As is, it would completely upend the meta.
Currently spanner heals the equivalent of 20HP/s if used optimally, pipe wrench and FSK heal 24/HPs and the mallet is at 27.8HP/s but will often lose some of that to overheal.
The armor kit in PvE currently adds 312 armor with a 6 sec cooldown - this is the equivalent of 52HP/s. So from a pure numbers perspective, we would have to start by halving the armor amount or doubling the cooldown.
And then we get to all the other concerns:
-The armor added is actually "armor" and thus takes piercing damage but resists other damage types. This would completely invalidate most guns that aim to disable components or the balloon. ie. armor added to the balloon means that suddenly the flechette/flechette lumberjack deals almost no damage to the balloon.
-The armor would also allow for more tool burn
-And it allows for abusing lochnagar
-It might also make ships too easy to keep alive. The game depends on piercing weapons being able to deal enough damage that they cannot be out repaired fully. It is quite possible that adding 312 armor into the equation everywhere might make it very hard to ever get kills (against a well-crewed ship).
TLDR, it would need to function differently than it currently does in PvE, otherwise way to many other things would need to be rebalanced to accommodate it.