Here is my perenial suggestion for knifefighters (copied from another thread):
It may be suboptimal mechanically as compared to other feat choices for your character, but combining your Dagger with grappling fits with my understanding of the way that daggers were used historically. Rather than held overhand and thrust upwards, illustrated medieval manuals show the dagger used underhand, thrust downward from overhead to target the neck, throat, and soft tissue above the clavicle. Basically, the technique is to grab your opponenet and stab downwards.
The feats that would simulate this are Knifefighter, a FR regional feat, Scorpion's Grasp (DU), and (obviously) Improved Grapple (which requires Improved Unarmed Strike.)
(A level of Monk would clearly help. And I don't see any reason why Knifefighter couldn't be treated as a regular General feat, instead of a regional feat--- unless you're playing Forgotten Realms, I guess. )
The primary mechanical advantage would be that many opponents would be unable to use their (one-handed or two-handed) weapons, and most of those with light weapons or natural attacks would still have a -4 penalty to those attacks.
Effectively, you're netting a +4 bonus to your own dagger attacks while grappling (because the usual penalty is eliminated) and a +4 bonus to your AC (the -4 to your opponent's own attacks.) An opponent who relies on one-handed or two-handed weapons will be at a tremendous disadvantage.
The greatest drawback would be the loss of Dexterity bonus against other opponents outside of the grapple. You'd also have to watch out for Monks and Bo9S characters with that (Raging Mongoose?) feat that allows them to use their weapons in a grapple.
Still and all, it's not too shabby mechanically, and it's just cool thematically to mimic the historical method.
Here are the feats:
Knifefighter
[Regional]
(PGF p40)
Must be from one of the following races & regions:
Half-Elf – Dambrath, Dragon Coast
Halfling – Channath Vale
Human – Anauroch, Dambrath, Lake of Steam, Sword Coast
Planetouched – Chessenta
You may use a Light weapon to attack your opponent in a Grapple
with no penalty on the attack roll.
You do not need to make a Grapple check to draw a light weapon
while Grappling (though it still costs a Move Action).
If your base attack bonus is +6 or higher, you may make a Full
Attack with a Light weapon while Grappling as long as it is already
in your hand.
Scorpion’s Grasp
[General]
(DU120 p35)
Strength 13
Dexterity 13
Improved Grapple
Improved Unarmed Strike
If you hit a creature with a One-Handed or Light weapon, deal damage normally and then you have the
option of starting a Grapple as a Free Action without provoking an Attack of Opportunity (no touch
needed).
If a grapple is started and you were wielding a One-Handed weapon, you drop it.
If a grapple is started and you were wielding a Light weapon, you may continue holding it. Each round, you
may attack your grappled foe as normal with it, except you do not have the standard –4 penalty
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