Fiend of Possession and Magic Item

[Yogibear41]

What kind of action is it for a Fiend of Possession to change the qualities it is bestowing on a weapon it is possessing?

For example say whoever is wielding the weapon is fighting undead when suddenly an evil outsider shows up and he wants to switch an undead bane on the weapon to an evil outsider bane, would this be a standard action taken by the possessing creature? or some other type of action?

[Biffoniacus_Furiou]

It's a supernatural ability (http://www.d20srd.org/srd/specialAbilities.htm#supernaturalAbilities), which always takes a standard action to activate unless the ability itself says otherwise.