Weapon Enchantments for my Bolts Ace's Heavy Cross-Bow

[Nosta1300]

I have wealth of a 10th level character and am planning to buy a Heavy Cross bow with uo to +3 Bonus

I know just going the +3 can be good but was wondering if there is any note worthy + 1 or 2 Enchantment I could pick.

Are main enemies are Dragons and Demon's
I know I could go holy but am not really feeling it

[VoodistMonk]

Flat bonuses are usually best. Holy can be awesome, but I really appreciate good old flat bonuses. Just pump up that +X as high as you can, don't worry about that fancy situational $#!+...

Crossbow Training bumps the crit multiplier up a step, which has always made me use the Dwarven Pellet Bow... it's a crossbow that does bludgeoning damage, and normally has a 19-20/×3 crit profile. With the aforementioned Crossbow Training, this becomes 19-20/×4. And with the Improved Critical feat, that becomes 17-20/×4... it is really difficult to get a better critical profile for any weapon in the game, and this is a ranged weapon!

[Java Man]

For a ranged weapon I am a big fan of bane ammo. Seeking and cyclonic enhancements on the weapon if you find that concealment or wind are common issues.

[thistledown]

Seeking is great, but at level 12 you can get Improved Precise Shot to deal with that problem instead.

If your GM will allow it, ask for the Truthful enchantment (It says melee only, so not legal by default). Great for ignoring the BS that casters put up to try and stay alive.

If you don't have a bard, I'm also a fan of the Lesser Designating enchantment. Every time you hit, all your melee allies get +2 to hit and damage against that target for a round. The greater version is +4 to hit and +6 damage, but super expensive.