You are correct!
But it looks like that one is slightly weaker (by an entire -12 atk) and also is HP. So it's basically the exact same thing as the Disaster weapon.
EDIT: For the record, we're using 20 Debuff Grail buff, since 15 had rare resists. I'm not sure is 20 100% or not, but it should be pretty close.
EDIT: Just had half of Sniper Shot resisted, so going up to 25 then.