Like all +2 weapons, the DM will add +2 to the AC hit when using this weapon but the damage bonus has already been factored into the damage wheel.
+3 Deathcleaver
Any time the wielder of this weapon successfully hits and damages an enemy with this weapon, the wielder heals 1 HP.
Inflicts 10 points of Acid damage on a single target. If there are other eligible targets in the room, they each suffer 5 points of Acid damage. The victim gets no saving throw to mitigate the damage, but if the victim is resistant/immune to Acid that will be factored in.