This is what you have already (assuming you mean that you want the Rogue to be unable to stand up to frontline mobs, your sentence can be parsed either way). If that's what you want, I don't get what you're trying to say then.
What I don't like currently is that the Rogue and Fighter are too similar in many areas. Nearly the same AC, nearly the same damage dealing maneuver as their typical damage dealing maneuver. It's just boring. I want the Rogue to be able to fill a niche in combat that the fighter doesn't already sit in and do better.
AC is a simple number, up or down. My
Wizard has a 15 AC. It's not "too similar", it's "there are only so many numbers between 10 and 20ish". As for damage-dealing... so what if they have similar maneuvers? You've got a skill list twice as long as the Fighter, and so many other much more Rogue-like maneuvers to use. Sneak Attack is just a fallback if you really want to be able to deal some damage fast. If you're playing a Rogue, you're much better off using your skills to better effect, given Skill Mastery.