The effects of Wrestling are pretty clearly explained, but much is left to the fiction.
Like, I'm assuming that a grappled opponent can't just move away (or retreat), because he's in a wrestling hold.
On the other hand, there's nothing saying a grappled foe can't attack, other than the fiction. So, is that how it should be played? Or is my fighter assumed to still be (awkwardly) swinging his broadsword around until one of the grapplers yanks it away with a 1+ Disarm?