godan verb (-u)
put on armor; arm oneself
Specifically refers to donning armor or arming oneself for battle. A somewhat literary or historical term.
武士は戦の前に鎧う。
The samurai dons his armor before battle.
godan verb (-u)
wear; cover oneself with
Extended, rare use meaning to wear or cover oneself with something, not limited to armor. Often figurative or archaic.
彼は厚いコートで身を鎧った。
He covered himself with a thick coat.