2011-06-01 : In a multiplayer game, if an affected creature deals damage to two of your opponents simultaneously, the ability will trigger twice.

2011-06-01 : Only creatures you control on the battlefield when Arm with Aether resolves gain the ability. Creatures you gain control of later in the turn won’t be affected.

2011-06-01 : The affected creatures keep the ability even if another player gains control of them that turn. If such a creature deals damage to you, the ability will trigger, targeting a creature you control.

2011-06-01 : The granted ability triggers on all damage dealt by the creature to one of your opponents, not just combat damage.