How do magic weapon special abilities work when used in a different manner?

Question

If we look at the list of magic weapon special abilities we see that they're divided into two categories, Melee and Ranged, which designate the category of weapon they can be placed on. Some, like, Keen, have additional requirements listed for enchanting, while others, like Designating (Greater), work for all weapons of that type.

If we had a +1 Keen Dagger, when used as a thrown weapon would it have a critical threat range of 19-20 or 17-20?

Similarly, if we used Empty Quiver Style to make melee attacks with a +1 Greater Designating Composite Longbow, would it still grant allies the +4 morale bonus on melee attack rolls and a +6 morale bonus on melee damage rolls?

Answer 1

Rules as written, the +1 keen dagger and the +1 greater designating composite longbow still are melee weapons and ranged weapons, respectively, despite also being the opposite, and being used in the opposite manner in this particular case. Neither keen nor greater designating makes any reference to “melee attacks” or “ranged attacks,” so RAW they don’t care about how they are used, just that the weapons themselves qualify as “melee” or “ranged.”

Talk to your GM before you attempt this, though; I have to imagine a lot of GMs are not going to like it. Personally, and in my experience with other GMs I’ve played with, it’s been totally fine—and I’ve never had it cause an in-game problem—but it’s the kind of “‘abuse’ of a ‘technicality’” that many find distasteful about RAW, so even if it doesn’t really cause problems per se, GMs may well not want it around.