Great weapon master rework

You've learned to put the weight of a weapon to your advantage, letting its momentum empower your strikes. You gain the following benefits:

• On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
• As a bonus action you can roll a strength or dexterity saving throw to be able to one hand a heavy weapon/great weapon. on a successful save you only deal half damage, on fail, you deal half damage and have a disadvantage on a hit. (I.e a great sword does 2d6 damage but one handing it will deal 1d6). While one handing you may dual wield with a light or finesse weapon.