thanks for the reply. he doesn't really knows what he wants because he is new. he is doing fine at role playing but he is crappy at battles. the rest of the party is a little overpowered so we want him to keep up with us at combat. the party is unbalanced and he usually gets killed or runs away at battles because the monsters are tough for the rest of us but impossible for him. we use all 3 and 3.5 books even eberon, oriental and ravenloft. so the main target is to improve his ac attack and damage, specially damage, and do him more durable in combat. we will also rearrange his stats (18, 18, 16, 15, 14, 14). and for equipment he can take the basic the dmg provides for a 9 level rogue + 4000 gp
That stat line is insane.
Halfling Rogue 4/Swordsage 2/Swashbuckler 3
(Take Rogue, Swashbuckler, Swordsage, Swashbuckler, Rogue, Rogue, Rogue, Swordsage, Swashbuckler.
If your GM is lenient on multiclassing XP penalty do Rog, Swa, Swo, Swa, Rog, Rog, Swa, Swo, Rog instead; the final rogue level will help you top off skills. If GM is not lenient with multiclassing XP penalties, continue with pure Rogue levels (or appropriate prestige classes) to get more sneak attack damage, more skills, and eventually rogue special abilities; Swashbuckler is valid if multiclassing penalties are waived, to increase HP and get better BAB.)
Feats:
1: Two-weapon fighting
3: Shadow Blade (+DEX to damage with Shadow Hand weapons while in Shadow Hand stance)
6: Daring Outlaw (allows Swashbuckler levels to stack with Rogue levels for sneak attack dice, mainly)
9: Improved Two-Weapon Fighting
STR 12
DEX 20 (+2 from levels goes to 22)
CON 16
INT 18
WIS 15
CHA 14
Swashbuckler gets you Weapon Finesse as a bonus feat and +INT to damage.
There's an alternate class feature that replaces trap sense with the ability to do half sneak attack damage to otherwise crit-immune creatures when flanking; I'm away from my books so I don't remember where that's found.
At 8 you have an initiator level of 2 (swordsage levels)+6/2(from other levels)=5, which is high enough to take Assassin's Stance as your second stance. Take Island of Blades as your first stance. Now you have Wisdom to AC in light armor (but not with a shield, unfortunately, so ditch the shield; Wisdom to AC should make up for it), you can more easily flank (in Island of Blades stance) or do more sneak attack damage (Assassin's Stance gives you +2d6 sneak attack) and you have access to some maneuvers that give you the opportunity to make the opponent flat-footed or flank them; there's a very good Desert Wind Boost that lets you conjure a flanking elemental for 1 round as a swift action. Use daggers.
In Assassin's Stance the base damage per attack, before items, is:
1d3+6(DEX)+4(INT)+6D6 (Sneak Attack, if you qualify). 4 attacks on a full attack action.
Choose armor based on the final DEX modifier you get; be mindful that this can change. There's a light armor in Drow of the Underdark(I think) that provides a max dex of +10 if you want to be on the safe side; it has +1 base armor modifier.
DEX is your most important stat, CON, WIS, and INT are important secondary stats. But with that stat line you can afford that.
With 18 INT you can afford to max the combat-important rogue skills Tumble and Use Magic Device and keep the others (disable device, etc.) at a decent level. Both Swashbuckler and Swordsage have decent skill points per level and decent skill lists. With a little tactical help (easy flanks) from allies, this character should pull their own weight with little trouble.
[Edit: Error corrected. Daggers sized for Small creatures do 1d3, not 1d4. Sorry about that.
Further edit: Changed level progression for later skill point glut to help top off skills.]