It’s actually an inaccuracy with the skill description/tooltip, Enchant is fully effective with ranged weapons (no penalty).
http://theamazonbasin.com/wiki/index.php/Enchant
Despite what the skill tree description says, fire damage added by Enchant is not reduced to 1/3 when applied by a ranged attack.
Having said that, there is some odd behavior with Fire Skill Damage that causes ranged attacks to not have as much damage as melee weapons with Enchant (also applies to Venom). From the same link:
- +% FSD also applies to melee attacks at time of attack, so it will be applied a second time to melee fire attack damage added by Enchant, Holy Fire and items. Character screen displays +% FSD being applied to ranged fire attack damage as well, but this is not actually the case.
I’ve reported the inaccurate Enchant description/tooltip here, hopefully they fix it: