I have been wondering this for a long time. What in the world is "Keen"? It's not in the manual or anything.

Keen

This enchantment doubles the threat range of a weapon. Only slashing and piercing weapons can be enchanted to be keen. Basically you will hit more often with a Keen weapon. I use it on everything I can.
Market Price: +1 bonus.

Ohhhhhhhhhhhh. Thanks! Now to the itemwizard.....

*Keen* is a descriptive term for an ultra-sharp blade. In game terms, it doubles the effective range for critical hits. A normal longsword does a critical hit on a roll of 19 to 20, but a KEEN longsword does a critical on a roll of 17 to 20.

Adding improved critical to a Keen weapon will TRIPLE the critical hit range - so that keen longsword will now do critical damage on a die roll of 15 to 20!

As an aside the most dangerous weapons in terms of critical threat range are the scimitar and the rapier. Keen variants of those weapons will do criticals on die rolls of 12 to 20 if the improved critical feat is utilized. For overall damage potential however, a variant of the Scythe is the hands down winner. It has a critical threat range (again with the IC feat applied) of 18 to 20 but its crits do FOUR times normal damage!!

Massive crits are also a good idea on Keen weapons.

Since we're on this topic, What side effects does the "holy avenger" property do?

Non-paladin hands:
+2 weapon
25% dispel on hit

In paladin hands:
+5 weapon
25% dispel on hit
d6 divine damage vs evil
spell resistance 16

Keen weapons are awesome. Too bad they don't work on those pesky undead mobs you find all over hte place.

didn't want to start a new post for this, but where do you find this info in the book? I looked, but maybe I don't know what I'm looking for?

You mutter an ancient and foul curse towards the bioware employees who wrote it, and turn to actual ad&d rulebooks. In common with all bioware RPGs, the NWN manual lacks important details.

Agreed. The toolset and even a few lines on weapon design was all just ignored.

Cool, I can do that. At least I know I'm not totally stupid, that helps the ego just a little, later, I'm off to reference.