As I wrote, I put no skill points into any weapon mastery, so Shield and Sword is at level one.
As far as a glitch, I repeated the boss fight at Maxos Temple a few times as a learning experience and after one victory my magic melee went back down to the 40s range. This surprised me and I reloaded before looking to see if I was still under some status attack, but if no such attack is used in that fight then there is a glitch.
Thanks.