There is no maximum damage, meaning Spawning Power can increase the damage dealt by this weapon spell.
If this weapon spell is replaced by another weapon spell or is renewed before it would end, the damage of the original spell occurs when it is replaced.
If an ally under this weapon spell dies, the damage occurs upon death. Combine with Death Nova for a large AoE spike upon death, but keep in mind that the full damage of this spell will not be dealt in such a case.
Consider Echoing this spell for a devastating timed AoE spike by casting it on two melee allies.