Homebrew-ish item question

[Forkedwizard]

So in the past I allowed a player to pick up a bow used by a Solar Angel
https://www.d20pfsrd.com/bestiary/monster-listings/outsiders/angel/solar/

They then were able to use slaying arrow for each shot, which really made them overpowered.

So a year later, we discussing if that should have been even possible. Does the slaying arrow ability come from the Solar or the Solar bow? It is described as a supernatural ability...

Curious what you guys think.

[OmniMage]

It lists slaying arrow as a (su) ability. Therefore it is a supernatural ability of the angel.

[Quixote]

In 3rd, it was the bow. Pathfinder was careful to state it was an innate ability of the creature.