Aw3som3-117 wrote:
From Targets:
Some effects target or require an ally, or otherwise refer to an ally. This must be someone on your side, often another PC, but it might be a bystander you are trying to protect. You are not your own ally. If it isn’t clear, the GM decides who counts as an ally or an enemy.
As far as I'm aware this is the only official definition of what's meant by an "ally" in the rules. So, the question becomes: is a weapon "someone on your side"? I would say no. The ability's name doesn't override the fact that it's an inanimate object. However, if someone disagrees with me there's already a built in way to do so without the rule quoted above: "If it isn't clear, the GM decides who counts as an ally or an enemy."
Personally I think it's pretty clear, again notice the "who", not "what" even in the description where it says the GM decides, but if one determines that it's ambiguous the default answer is to ask the GM.
The part that really confused me and introduced the rules ambiguity is that the rules don't really define what constitutes a "someone" very well and the divine ally ability does this; "Your devotion attracts a spirit of your deity's alignment." which begin to inhabit said items when you pick either sword or shield. That's where the ambiguity for me lies, does being possessed by a spirit grant an item personhood?
edit: as an adendum to this question because it is related, do intelligent items count as persons?