according to what i see in some raid, in the future instead of 150 divine and devil souls, the last rewards will be 250 divine and 100 devil souls.
about the rewards itself, looking in jack O latern event (200 divine and 100 devil) you can get 4 copies of the weapon and 5 of the eidolon.
not sure about the drop in gacha, but it seen like at least in this event you can MLB jack O latern and the the weapon just from getting the right amount of devil/divine souls.