It ties in nicely into the skill crafting thing too, now that I think about it.
Since all of those are a flavored variations of the basic skill: Throwing Knife.
Evolving skills is nice way how to reduce skill explosion which suffered DOS1 late in game. It looks to me that Larians are trying to fight this with memory, but you still have a load of skills in the book. So, finaly you will scroll up and down in the book before combat ... if combat is not ok then load and select another deck. Chmm.
I thinkg that evolving skills might be implemented in the current game.
Just a note, do I understand correctly that when you get better skill then older is replaced ?