Hi there! Let me translate you what I'm able to see in the spanish Chaos Lord warscroll card.
You have to choose one of the three different weapons: Reaper blade, deamonbound steel and deamonbound flail (in that orden of apearance in the stats).
Deamonbound weapon. If the unmodified hit roll for an attack made is 6, that attack inflicts 1 mortal wound on the target in addition to any normal damage.
Sorry but the command ability is to small to guess!!