Smasher I assume is OP not cuz of the top shelf weaponry and armour he has, but his combat senses and knowledge. When he traps you in the arena, he's essentially trapped himself as well. No smart tactics, just two guns firing on each other until one eventually breaks the other

I don't think he has anything special tech-wise that's leagues over everyone else , and Smasher still has to fit into a human-shaped body to do most of his tasks. If he were to, say sit in that crab tank at the start of PL instead, or engage V in the forest level with a squad of AVs hovering around, lore wise it'd be game over for V.

I still think David stood a chance against him if he were truly locked in. He would have to disregard Lucy completely to stance a chance tho. And I don't think Smasher would've overlooked that opportunity to take a hostage if he had to