does sword/blunt weapon mastery apply to 2h sword/blunt? if so does it stack with 2h weapon mastery?
Yes they stack.
Sword/blunt mastery applies to both 1H and 2H weapons.
2H Mastery stacks on top of that when a weapon is 2H.
2H Mastery at maximum level basically doubles the Patk bonus of Sword/blunt and adds 3 Accuracy. It doesn't double your patk, just the mastery amounts. (~130 Patk) You get the +3 ACC at level one of the skill.