Some special attacks such as Trip can be performed with weapons. Its text says:
Some weapons can be used to make trip attacks. In this case, you make a melee touch attack with the weapon instead of an unarmed melee touch attack, and you don’t provoke an attack of opportunity.
Supposing I am using a Flail (or other weapon which allows tripping with it) and I have Weapon Focus with the Flail, do I add the Weapon Focus bonus to the Trip check (i.e., the melee touch attack with the flail)?
P.s.: similar to this question, but I want an answer for D&D 3.5 instead of Pathfinder