Easy, simple. Weapons that knock back ships.
This effect is already in game, sort of. Ive seen engineless ships be pushed back by weapons. Ive also seen them pushed forward
It might be an interesting mechanic. Works better against light (and thus, probably faster) ships, and less against heavy. Though this of course isnt definate.
I would think short-ish range. Prehaps enough to knock some ships out of cruiser laser range? Would go well with those longer range weapons, as they tend to have larger minimum ranges.
Also provides an itneresting choice for a player, to get close with a light ship, fast, or close close in with your super heavy melee guys.
Been think of this for quite a while, decided to post it so i can claim it as my own.