Zebuxuruk is trapped in the Plane of Time, doubt he's the boss. That dragon may be the guardian and boss of the zone that is keeping Zeb in chains so he can't go around telling mortals secrets of the gods anymore.
As for the weapons, they are now part of the models, not an actual item. So killing Rallos doesn't mean he's gonna drop that axe. Just like when AL and FOH killed Mith Marr they didn't get that cool looking blue flame sword.
Also if you look at the pic, RZ VZ and TZ are Hitting each other. Not slashing. Probably because if you give them weapons the weapons show on top of the model weapon.
