If he had a trident with him, he'd be jabbing it upwards into the heart of his opponent. Without a weapon, it's harder, but hard doesn't frighten Finnick. What's hard to someone who survived the Hunger Games? Who's watched people he's responsible for go into the arena to die year after year after year?

And nobody in the Hunger Games would be stupid enough to pull a move like that. You get someone on the ground, you take them out, you don't stand and gloat. Because if you do that, you're going to get the tables turned on you.

A lifetime on and off boats, in and out of training, living with a trident as an extension of himself, has given Finnick upper body strength far beyond most, and years of combat experience and training have given him the ability to leverage it, which he does, by grabbing the leg perched on top of him and twisting, throwing his upper body into upending the creature so he can spring to his feet.