I have just a quick question.
Say I have a +2 Adaptive composite longbow, and I would like to add flaming.
Would I have to pay for an additional +1 bonus to add the Flaming ability, or would I be able to "buy" the ability with a +1 bonus already on the bow?
In the first example if I understand the idea correctly the bow would become a +2 Flaming Adaptive composite longbow at the cost of 10k
In the second example if I understand the idea correctly the bow would become a +1 Flaming Adaptive composite longbow at no additional cost.
Am I correct in that both examples would work, or is the first example the only way to make this happen?
Only the first example works. You have to add the flaming property to your weapon. It does not replace any enhancement already placed on the weapon. So, to add flaming, you would need to "make" what is effectively a +3 weapon, since it is already +2. It will cost you 10,000 gp.
Fretgod has it spot-on.
Extremely minor nit-pick time: Enchantment is a specific school of magic. Weapons tend not to have enchantments. (Yes, I did understand the question, but I came to this thread hoping that the OP was asking about adding a charm monster ability to a weapon that functions on a hit. Because that would be funny and cool.)