What do you mean he won't use it? SNI will passively tell him, and what do you mean waiting for his ego to calm down? Gil here isn't bloodlust and he's not stupid either, Accel isn't the type of person Gil would underestimate, also Gil doesn't consider any sword special unlike EA, he just easily throws it at the enemy, simple. They only know the basics of Gil's abilities and are constantly curbing Gil's abilities, so what's wrong with me telling some Gilgamesh wincons?
No. If he never reflects on abstract things like concepts then it's useless, reflect higher dimensional things doesn't mean reflect abstract things like concepts because it's both physically and supernaturally different.