Just a quick question is The Storm Glaive worth fighting the Harpies for, or should I bring Agni with me.
Not really IMO. I tossed a Leanstone at them and blew them off the mountain, I thought that would just leave them start in a staggered position but it actually just outright defeats them if your Agility is good. No real regrets not getting it though, there are better options for the two-handed spellblade route, like the Spiraled Blade, Elthara's scythe, or the hammer in Rynquest.

