Arc Lash is obviously a spell for all intents and purposes, but it is strictly a melee-range attack and should be treated that way mechanically. If you assign a Rogue’s cutthroat (melee) basic attack to right-click, your character will move with right-click until it contacts a mob and then will attack it. Alternatively, if you do the same with a marksman (ranged) basic attack your character will stand still and attack. With those examples, currently, Arc Lash is treated as a ranged attack when it should be treated as a melee attack. Necromancer’s basic attack Reap is not exactly a melee range attack, but I think it would benefit from this change as well.
I also have a suggestion while I’m on the subject. All basic skills should be treated with lower cast priority than any other skill or spell. If I am using a basic attack and try to cast something else, the basic attack should be instantly negated to allow the other cast to happen as long as the resources to use it are available. Combat feels a bit clunky and I think this would help with that.