Blade mastery increases nominal, magical and physical loss of the sword, Axe mastery - of axe and club, but Shaft mastery – of spear and staff, Dagger mastery – increases loss of the dagger. Passively increases the nominal loss of weapon for the loss multiplied on the skill level. In this way, with the 3rd skill level, 150/300 will get added to the loss of weapon with base 50/100. Works all the time.