Geo remembered Aspida's words when the old Fulgeo tried to gain her favor. "You are not your brothers, stop trying to be. No matter how hard you work you will never be them."
It was this sentence that broke the original Fulgeo's heart which prompted him to kill himself. Kohei on the other hand understood what Aspida was trying to say. "I can never be them because I am myself. Copying them will never work as I am not them."
Unlike his brothers Geo had Mana. In general, Valorious did not look favorably at people with multiple Calibers. This mainly stemmed from the fact that it takes an insane amount of training and patience to even get good at using one of them.
The number of people who could do that for two completely different branches of combat was incredibly small. Like being armed with an axe and a dagger. The two are both melee weapons but each had its preferred distance.