I know you asked where you could find them, and not if you should use them or not, but I would highly suggest just getting the app3s of those skills. The prices that the NPCs sell can be a little higher than what you can get an app3 for from a player when dealing with Scout Runes and Fighter Essences, which are in much lower demand. Especially Fighter Essences, since a Scholar can make these from scratch themselves, with no dependencies from any other crafters. Have fun!