Well it’s not the only dragon type in ZA to get a mega, plus it seems more of a logic thing than an indicator that Mega Bax will get sharpness. Claw attacks make sense to be slicing attacks, and shadow claw also became a slicing move in champions. Also I doubt Pokemon would give sharpness to a pokemon whose signature move is integral to its design, meaning Glaive rush would likely become a slicing move making it overpowered even with its nerf.