I can see why late-game would be a problem for ya. The problem with building Aatrox around his W like that, is you force the majority of his damage into single target. Personally, I prefer going with a CDR build, focusing on stacking his passive through abilities. Runes, I go AD reds, AD quints, AR yellows, and MR blues. I pick up TL with the extra 5% CDR from masteries. I try to rush either BC or Ravenous Hydra, depending on the matchup. From there I'll round out my build, normally ending up with something like:
and
or 
You get pretty good late-game damage out of this, since more of your damage is focused in your Q and E, and their low CD's means you can cast them a couple times in a teamfight, you have decent health and resists, so you don't pop like a balloon, and you have good splitpush, still, since you have tons of waveclear, and your passive allows you to take turrets pretty quickly.