Mastersmith's roll is to break enemy gear, with Meltdown/Shattering Strike. This is done best with Tomahawk Throw alongside Snipers in the back row. They can fight enemy emp breakers in dire situations with Cart Termination/HSCR. They can also portal guard with card revo & meltdown buff which never misses target outside of safety wall.
SVD and Strength-Agi-Vit both work for the role.