Penalties when dealing Subdual damage with a lethal weapon

Is there a feat out there that allows you to remove the -4 to hit when attacking in subdual with a lethal weapon?
I know the Merciful magical weapon property can do this in a round-a-bout way but I am looking for a feat. I am creating a guild of vigilantes and would want a way for it's members of dealing subdual damage with their weapon of choice when they want to take in a bad guy rather than kill him. Since it would be quite expensive (not to mention unrealistic) for everyone of them to have a Merciful weapon, I would give them a feat and make it part of their Vigilante training.

thanks in advance

Blade of Mercy (Sarenrae religion trait) allows you to ignore the penalty entirely with slashing weapons (including daggers!), AND gives you +1 nonlethal damage on top of it. Of course, this requires everybody worship Sarenrae, so it may not be an option.

Weapons of Peace trait reduces it to -2. It's worthy of notice.

Bludgeoner feat allows it for bludgeoning weapons.

Order of the Blue Rose Cavaliers can do it with any weapon and get a +2 to damage and seems to fit your group well overall. Make them Huntsmasters to ditch the horse and knightly feel and they look more like members of a hunting lodge, giving you a nice base for the group unless you already have one.

Monks, Brawlers and Order of the Hammer Cavaliers can all do it bare handed.

Anyone with IUS can deal lethal or non-lethal at their choice.

Anyone with EWP: Whip, Weapon Focus (whip), BAB +2 and Whip Mastery can do lethal or non-lethal, their choice, no penalty, with a 15' reach weapon.

There is a feat in 3.5 called subduing strike that just flatout removes the penalty for all melee weapons. I as a gm wouldn't see any problem with allowing it at my table, there are way more powerful options to spend a feat on.

Subduing strike it is. Despite the fact that I do like the blue rose cavalier idea I am a player in this game so it would be very hard to recruit only blue roses lol. Thanks for the input everyone

Rogue Genius Games also has a Nonlethal Force feat that does this ...

I'd swear I saw a feat on the ogc site that allowed it, but it had like two feat prereqs and a BAB prereq as well ... now I can't find it.