Just to recall my OP post, I'm not complaining about how to use magic in LoG, because I like it. Selecting the runes while avoiding mobs to cast a spell is fun. If you want to talk about that, there are so many others posts to do so. No need to reply here
OP was about the learning and discovering issue of spells in the game, and the fact that you are kinda forced to train in a specific school to unlock 1 spot for 1 spell of this school (and the one dev putted at this place in the school tree).
As someone said before, no, my tank had 0 pts in axe and could use an axe, and a sword, and whatever he found. Maybe later in the game weapons will have prerequisite, but yet he can equip what he wants. Same for my rogue.
School tree of melee characters just give more stats / power for a specific type of weapon,
but none are mandatory to use a weapon.
For casters,
school tree are mandatory to be able to cast (it seems, but I can be wrong), that's what I find a bit "unfair" and boring for my caster.
And please, for further replies (if any

), just don't speak about "but I prefer using no runes ! I prefer a button for each spell !"... because it's not what's talked about here...