Shape and Material bonus -- horn?

My player is making a composite bow to enchant. One of the main materials in making this is animal horn. (he'll be using Pyranaen Ibex horn)

Anyone have any thoughts on what bonus this might have?

The only thing that comes to mind is "summoning+3" (like a hunters horn).

Horned animals were often associated with strength and wisdom.

Of course, it's also an important phallic symbol...

Drinking (but I doubt this is relevant to a bow).

Striking fear or impressing opponents (any number of live horned animals have this non-magical effect)

do you think "alter emotions +2" might be appropriate?

In many parts of Europe (e.g. Italy) horns are traditionally associated to warding off bad luck. This is, however, generally more associated to shape than to material. Thus making the "horn sign" (tightening a hand into a fist with forefinger and little finger extended) is a common reaction to the prospect of some ill fortune, but e.g. a buckle made of horn is not considered particularly potent against it.