As per magical weapons, is the enhancement bonus in ALL circumstances limited to +5?
A single weapon cannot have a modified bonus (enhancement bonus plus special ability bonus equivalents, including those from character abilities and spells) higher than +10.
It's a lot less specific about the actual enhancement bonus, however. Say if I had a +4 Sword of BBEG Slaying, and (by class ability or spell) added Bane BBEG, would it cap at +5, or function as a +6?
It's my understanding that, in the scenario you outlined, the sword would function as +6 for slaying BBEGs, similar to the way a +5 Furious Great Axe will function as a +7 Greataxe in the hands of a raging Barbarian, even though it's got a total of +6 in enchantments.
A +5 dragon bane dancing greatsword is a legal weapon. Against a dragon, it would function as a +7 dragon bane dancing greatsword, but that doesn't increase its price at all (or put it over the limit of +10 weapon enhancements).
