This is just a couple hours dalliance. It hasn't really been seasoned with flavor yet. I haven't played with builds to see how broken it is or anything like that, just a mental exercise and a starting point.
Haven't been with pathfinder long, so if I am not speaking the language correctly I apologize.
It is written as a 10 level base class, but could be modified to be a prestige class easily. Hit Die was left a d8 purposely. Slow progression on sneak attack, going back to rogue gives her a +17 at 20th level and devastating 7d8 sneak attack, too much? Maybe.
Like I said, a mental exercise that with some tweaking might be a viable option for some people. Throw your expertise at it.
Thug
A Thug is a rogue who is more concerned with the martial aspects of the craft.
Alignment: Any.
Hit Die: d8.
Class Skills
The Thug's class skills are Acrobatics (Dex), Appraise (Int), Climb (Str), Craft (Int), Disable Device (Dex), Escape Artist (Dex), Knowledge (dungeoneering) (Int), Knowledge (local) (Int), Perception (Wis), Profession (Wis), Sense Motive (Wis), Sleight of Hand (Dex), Stealth (Dex), Survival (Wis), and Swim (Str).
Skill Ranks per Level: 6 + Int modifier.
High bab
High fortitude & reflex
Weapon and Armor Proficiency: Thugs are proficient with all simple weapons, plus the hand crossbow, rapier, sap, shortbow, and short sword. They are proficient with light and medium armor, but not with shields.
1st Weapons Training, Trapfinding
2nd Rogue talent
3rd Bonus Combat feat
4th Sneak Attack 1d6
5th Precise Weapon
6th Improved Weapons Training
7th Rogue talent
8th Bonus Combat feat
9th Sneak Attack 2d6
10th Precise Strike
Weapon training: At 1st level the thug becomes proficient in piercing martial weapons.
Other skills as Rogue
Precise Weapon: At 5th level a thug can select one piercing martial weapon that she will be able to use to make sneak attacks. In a full round action this attack can only be used on her first attack. It only applies if the Thug is using her chosen weapon as her primary weapon.
Improved Weapons Training: At 6th level a thug may select one from the following;
First, the thug may select another class of martial weapons to gain proficiency in, slashing or bludgeoning.
Second, the thug has the option to select one exotic weapon as the exotic weapon proficiency feat. The thug can, if the weapon is one handed and a piercing weapon, designate it as her chosen weapon, replacing her previous choice.
Third, Catch off Guard feat
Precise Strike: At 10th level a thugs expertise with her chosen weapon allows her to make more devastating attacks. All sneak attack damage with that weapon is now does extra damage, rolling a d8 instead of the standard d6.