Now that we have a fight they drop from. Got 3 SupV+ in about 6 hours slaming him... mine were guts, potion hoarder and rupies tycoon tho. Did another session next day, another 6 hour grind got 2 more, 1 was quick cd other rupies tycoon again lmao. Still never fing seen one from a curio tho.
If its anything like Tweyen(havent built siete yet) if you can get max crit rate, you only need 1 crit sigil for 100%. free up imbue stone for something else