[WOLFGIR]

Best way is to open up the weapons already present in the game and see the differencies.

Keen doubles the natural critical range as described above.

attack bonus gives plus to hit, enhancement gives plus to hit and damage. Bonus damage adds a bonus damage on hit. Massive criticals adds extra damage on a critical hit.

The rest is too much to describe here, fool around a little, everytime you make a change hit the first tab for the general informatin about the item and you can see the changes summerized there, most of them. Be aware that many abilities increases the level requirements.

If you like to know more, there are books about this and I think that some of the websites dedicated to NWN has lists like this online.