Of course you know, what you've to do after your first playthrough, but this argument wouldn't only apply to FoW (f.e. ambush spawning).
FoW includes strategy. Gradvius explained it well.
I actually like this idea especially the penalties for effective weapons.
It gives you the choice either to take the risk to kill an enemy instantly with an effective weapon and being doubled by the enemies or to play carefully by not using it.
However penalties for brave weapons would kill the "brave effect" of attacking four times. These made them kinda pointless except for the first two attacks..