Gangs don't work for a few reasons.

Firstly, seven winds of hamsah mu'tazz. It's sort of obscene.

Secondly, ganks tend to focus on lagging. Lagging doesn't kill dexy sword specs, especially not when you're eating tons of ripostes a round. Something I've covered before in great detail. The best way to deal with dexy sword spec if run them out of preps and burst damage when they overextend. They don't have much hp, and they will overextend. Catch an elf/dark-elf sword spec with only minimal protection and you can burst them with a good flurry/drum/ambush/savage feedings etc.

There's a time and a place for a gank. Killing dexy sword spec isn't one of them unless its a group on group fight and your allies are intelligent enough to focus their melee at a third party while directing targeted strikes toward the dexy sword spec.

Third option is to outfight them as another warrior. Either another dexy sword spec or, surprisingly, I find a decked polespec/spear spec to be a reaaaally hard fight for a sword spec 1v1. The good polearms prog, you hardly ever riposte them, and they have pretty solid targeted damage in chop/pugil.