Originally Posted by Flickerdart
Why is this a problem? I don't need to know the particular sub-species of this dire wererhino to know that creatures that are covered in armoured plates can be stabbed in the eyes, or that you can use the weight of such a creature against them to wedge your blade in further...
The same thing exists with the Ranger's Favored Enemy. You might not know one dragon from another, but you know where to stab the lot of them so that they bleed the most.
Firstly, Knowledge Devotion and Favored Enemy do not care about sub-species. They only care about creature type. It has nothing to do with stabbing armor covered creatures in the face, or using their weight against them. It has everything to do with understanding the creature itself.
Secondly, static DC's for checks of this nature giving combat bonuses are bad design. By level 10 it is trivially easy for a cleric to hit the +4 and +5 range on every single check against every single type in the game. This is boring and does not make sense in regards to the game world.
Of course, YMMV, but in my experience most DM's (including myself) find it stupid that you can gain combat bonuses through knowledge when you don't actually know what you are fighting.