I'm sketchy about the one armed protagonist. Might have only been missing a hand. Also might have been a good/great swordsman before losing the arm. He may have been on a quest to restore his arm.
Hunt for the novel was triggered by seeing the name Tycho, who may have been a supporting character or military leader, and was possibly a construct. The term homunculus comes to mind.
I don't recall the protagonist having any supernatural powers, though there was magic present in the world.
Book might have been considered Young Adult, hard to tell now since I was reading all sorts of fiction back then. Time frame read was approximately 15-20 years ago. If it was part of a series, I only ever read this one book.
Will attempt to come up with more details over the weekend.