I'm an actual owner of this weapon. I figured I'd post some of the information I've come across while wielding it.
I have had this weapon for almost a year now. Many people underestimate it due comparing with other relic weapons. Yeah, it may not be the best statwise compared to things like Apocalypse, but it does have its own strengths that people seem to overlook. Acc+20 on a GS will open up possibilities to use attack elsewhere. And you can't go wrong with a 10% Critical hit rate increase from the weapon itself.
Scourge itself is a weak WS in terms of damage, considering it is modded by MND and CHR, but it gives the aftermath of critical hit rate increase (which is parsed to be 10%). 10% Crit rate from Aftermath on top of a 10% crit rate on the weapon itself sounds like a win to me. A good side to using Scourge is that you can now close/open both sides of Light with one weapon, (assuming of course that you're skillchaining.) Spinning Slash is Fragmentation based, while Scourge is Fusion based.
A downside to Ragnarok is not being able to do a 6-hit build, however, it will not matter. You'll be swinging fast enough where it won't make a difference.