Slightly more complex/cheesier (ECL 15 build):
Whisper Gnome Martial Rogue 8 / Swashbuckler 3/ Unarmed Swordsage 2 / Hit and Run Fighter 2
Progression: Rogue 1, Swash 3, Rogue +2, SS 2, Rogue +1, Fighter 2, Rogue +4
Str 12, Dex 18, Con 16, Int 14, Wis 10, Cha 8 (32 PB)
Str 12 (14), Dex 21 (27), Con 16 (18), Int 14 (16), Wis 10 (14), Cha 8 (10) (final)
Alt. Class Features: Martial Rogue (replace SA w/ Fighter feat progression), Arcane Stunt (Use Blur as a swift action for 1 round each time; replaces Grace +1), Penetrating Strike (replace Trapsense for 1/2 SA damage to those immune), Unarmed Swordsage (Lose proficiencies you have anyway for Monk unarmed strike progression), Hit and Run Fighter (+2 initiative, +Dex to damage vs. flat-footed foes, lose heavy armor and tower shield proficiency)
Feats:
Mobility (from +1 armor enhancement; MIC)
1 Dodge
1 Combat Reflexes [flaw]
1 Deft Opportunist [flaw]
1 Titan Fighting [Rogue 1]
2 Weapon Finesse [Swash 1]
3 Combat Expertise
5 Backstab [Rogue 2]
6 Opportunistic Tactician (or Sidestep...same benefit)
7 Weapon Focus (Shadow Hand) [Swordsage 1]
7 Improved Unarmed Strike [Swordsage 1]
9 Shadow Blade
9 Derring-do [Rogue 4]
10 Elusive Target [Fighter 1]
11 Singlehanded Victory [Fighter 2]
12 Staggering Strike
13 Adaptive Style [Rogue 6]
15 Craven
15 Expert Tactician [Rogue 8]
Flaws: pick 2
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Feats explained
Deft Opportunist: +4 to hit on AoOs
Titan Fighting: Dodge feat is +4 vs. anything larger than you
Backstab: If you flank a foe and he doesn't attack you, he provokes an AoO
Opportunistic Tactician: Free 5' step after each AoO
Elusive Target: Just read...
Elusive target - Feat - D&D Toolshop
Shadow Blade: +Dex to damage w/ SH weapons
Staggering Strike: Anyone hit by your melee SA must fort save (DC ) or be staggered for 1 round
Adaptive Style: Refresh and change readied maneuvers as full round action
Craven: +HD damage with sneak attack, -2 saves vs. fear
Expert Tactician: You and allies have +2 circumstance to attack/damage for 1 round vs. any foe you hit with AoO
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Maneuvers (IL 8):
1 Distracting Ember R
1 Counter Charge R
2 Cloak of Deception R
2 Flashing Sun
2 Mountain Hammer
3 Soaring Raptor Strike R (note: use novice TC item to qualify)
Stances:
1 Island of Blades (Flank with allies on any enemy you are both adjacent to)
3 Assassin's Stance (+2d6 SA)
[sblock]MAD enough?

Basically, base weapon damage is crap, but he adds a lot to it. And once he gets into a flank, whether you attack and miss him or go after someone else, you're pretty hosed. Unarmed Swordsage is not at all necessary, it's just free bonuses, and...should you lose your weapon, unarmed strike IS a finesseable "one-handed" shadow hand weapon, so good back up...[/sblock]