I feel that if Vengeance is included, it would have to be against the person responsible for sticking a tadpole in your head. Selecting from a menu is back to the problems with ranger Favoured Enemy.
Having thought more about it, my guess is that they are going to default Vengeance to undead/fiends (since it has bonuses against them) or generic "chivalrous enforcer of justice" which means they are going to role-play exactly like Devotion.
