Don't use elemental mods on glaive prime. The only thing you care about boosting is Glaive P's forced slash proc. Things like Initial Combo, Crit Chance and Damage, Faction Damage, and Melee Damage are the only thing that interest you.

Here's (in my opinion) BIS no-riven glaive 2 forma build. Any mod you dont have can be replaced with its regular version, but if you can, get Amalgam Organ Shatter ASAP due to extra wind up speed. If you wanna make it 1 forma you can just use primed pressure point, the difference is minimal.

Build

Another thing worth getting is some kind of Viral-spreading secondary weapon. Or the Panzer Vulp pet.

You throw the glaive by holding melee key, then detonate it midair with Heavy Attack button. And everything dies.