Gauntlet axe

Superior one-handed melee weapon
Cost: 25 gp
Damage: 1d8
Proficient: +2
Weight: 3 lb.

This heavy bracer holds two light crescent blades, turning the forearm into an axe while keeping the hand free. The weapon can also serve as a light shield. A gauntlet axe can be enchanted as either an arms slot item or as a magic weapon. When enchanted as a magic weapon, it does not occupy a character’s arms slot.

Defensive (A defensive weapon grants you a +1 bonus to AC while you wield the defensive weapon in one hand and wield another melee weapon in your other hand. Wielding more than one defensive weapon does not increase this bonus. To gain this benefit, you need not attack with the defensive weapon, but you must be proficient with it.).
Off-Hand (An off-hand weapon is light enough that you can hold it and attack effectively with it while holding a weapon in your main hand. You can’t attack with both weapons in the same turn, unless you have a power that lets you do so, but you can attack with either weapon.).

Axe (Axes are weapons that have bladed, heavy heads and deal vicious cuts. An axe’s weight makes it fine for delivering crushing blows.).

Published in Dark Sun Campaign Setting, page(s) 121.