Training Enhancement on Brass Knuckles

[Arassuil]

Hopefully this is an easy question to answer. Can you put the Training weapon enhancement on Brass Knuckles?

Training Enhancement wrote:

Source Inner Sea Intrigue pg. 52

Aura faint transmutation CL 3rd
Slot none; Price +1 bonus; Weight —
Description
Popular among those who seek to impersonate skilled warriors, a training weapon grants one combat feat to the wielder as long as the weapon is drawn and in hand. The feat is chosen when this special ability is placed on the weapon. That feat cannot be used as a prerequisite for any other feats and functions for the wielder only if she meets its prerequisites. Once chosen, the feat stored in the weapon cannot be changed.
Construction
Requirements Craft Magic Arms and Armor, magic weapon, creator must have the chosen combat feat and its prerequisites; Price —

I guess what it boils down to, is whether Brass Knuckles can be "drawn and in hand"? Armor Spikes, Cestus/Spiked Gauntlet, etc. are probably a no.

In the case of Brass Knuckles, if I had to make a guess, I think the answer is yes, but I'm not 100% sure on that.

[Pizza Lord]

You should be fine. I read 'drawn and in hand' to be short for 'wielded in hand'. I think they didn't want 'wielder' and 'wielded' in the same sentence. As long as you have it drawn and you are wielding it, you should be able to benefit from it. There's nothing stopping the enchantment from being on other weapons that wouldn't apply, like a boulder helm or armor spikes, they just wouldn't be considered drawn or in hand, so you wouldn't benefit.

[toastedamphibian]

There is not really a consensus on this. Some say any weapon you can atrack with, others only weapons you physically hold in your palm. I think I recall someone claiming it only works on rounds you attack with it. You'll need to discuss it with your DM, probably.

Definitely needs some reigning in, lest you end up with everyone walking around with 2 gauntlets, 2 boot blades, armor spikes, shield and boulder helm of training. On the flip side, spiked barding of training seems cool, so I would recommend trying to agree on some sorr of middle ground.

[Diego Rossi]

Wielding a weapon sometime mean "actively use", sometime "have ready do use", sometime "have in your hand (even if for some reason you are unable to use it)". it all depend on the author use of the world.
The semi-official meaning of wielding is "actively use", but Paizo has never gone and updated all the books to that meaning.
The ability say "grants one combat feat to the wielder as long as the weapon is drawn and in hand". To my eyes the second part override the "wielder" part, so you need to have the weapon draw and in hand, but you don't need to be using it or even be able to use it.

So, theoretically, it is possible to have brass knuckles on your shield hand, use a use a shield and benefit from the training property.
I wouldn't allow it, but the ability text seem to permit it.

I would add the "able to use the weapon in the right situation" caveat to the requirements. As an example, a weapon with the Alertness feat will work if you have it in your hand and you could use it to attack a nearby foe if needed, even if the nearest foe is teens of feet away.
It would not work it it was brass knuckles and you where carrying a wounded companion in your arms.