It’s extremely rare, not particularly well known, difficult to work with, and not very durable. You saw how Darth Bortles’s helmet sustained lightsaber hits but broke from a punch. It has limited usefulness, but Sith armor is one use.
Nothing is so extremely rare that the empire wouldn’t have it. Arguing Palpatine wouldn’t have heard of it seems like a dead end. You can maybe argue palps wouldn’t give the separatists something that useful, but his dedicated jedi hunters would have had it.
It’s extremely rare, not particularly well known, difficult to work with, and not very durable. You saw how Darth Bortles’s helmet sustained lightsaber hits but broke from a punch. It has limited usefulness, but Sith armor is one use.
Nothing is so extremely rare that the empire wouldn’t have it. Arguing Palpatine wouldn’t have heard of it seems like a dead end. You can maybe argue palps wouldn’t give the separatists something that useful, but his dedicated jedi hunters would have had it.