Winter's Guile should work with Ball Lightning, Celestial Fire.
When I heard of the changes to top tree Dawnblade, I honestly got a little excited and started theory crafting some fun little builds. Nothing that would be considered OP or anything, but just some fun times.
My idea what Top Tree Dawn, Winter's Guile, and Monte Carlo.
The setup would have been eat grenade for Heat Rises, kill an ad with a winter's guile'd top tree melee, fire x5 Markov'd shots at another enemy to recharge melee, then throw a winter's guile'd x2 melee, repeat. Would have been fun to see how effective it would have been for ad clear and maybe some captains and stuff.
But Winter's Guile doesn't work with ranged melee. The exotic has kinda just sat there in everyone's vault (or collections for those that really don't care about it) ever since it came out. It never added anything to the game as you need kills to boost it. There are so many drawbacks to the exotic arms that it has actually NEVER been worth using for anything, even fun little builds.
So all I ask is for Winter's Guile to be allowed to work with the ranged melee attacks that warlocks have. That change won't even phase PVP, and it can only serve to make PVE more fun.