I honestly think Buster Sword in the past two months have been inferior to virtually all the other 5* swords and daggers, including non-SB ones, by sheer factor of no RS to use it on. Barring Danjuro, for the exact same reason.
I mean, even Greatsword++, a 2*++ (albeit on the high end of the 2* scale) outclassed Buster Sword for VI worlds. Galbadian Sword comes very close for VIII worlds. Both were given out for free via events. (Edit: fixed this paragraph)
That's about to change with a VII event and a few VII paintings though. Coupled with a lack of VII weapons in general it shoots from "decent" to "Godlike"
(p.s. hilariously enough I have a Buster Sword and a Danjuro, only two offensive 5*s)