So i ended up just waiting for him to turn again and then killing him with one of my squads. Im positive he was killed while in "Were" form but the strangest thing happened after. Couple months later i end up with one of my axeLORDS dead in a fight with another dwarf. He was just a trainee compared to the lord but more digging revealed the lord put down a stonecrafter that had (for whatever reason) began attacking him (not sparring, full fight) during training.
Start of a possible loyalty cascade? Unsure as of now and ill wait a little longer until then. But the current casualties stand at one axelord, a stonecrafter, and the possible cause, one lone werelizard dwarf.
Also no tavern exists so there's no chance of drunkenness being the cause. As far as i can tell the stonecrafter just randomly started attacking the axelord who promptly killed him, and then found himself falling to a comrades axe from a separate squad (they also train in separate areas many Z-levels apart).
I don't know as of now if that particular axe lord dealt the killing blow to the werebeast, but multiple dwarfs attacked the beast and so far no one else has been killed.
Final note, seams the axe dwarf that killed the lord is missing all his teeth, probally got punched out or something during his brawl...