Originally Posted by
Sparton_LOTB
A single instance of any summon session can be better or worse than average, but I'm sure if you look at your collection of characters now, you'll probably find that there's going to be more high-rarity Gunners and Assassins that you're missing compared to Warriors, Magus', or Sentinels. For newer players, any soul that can give higher rarities is great, but especially with sacrifice allowing you to "trade up" bulk amounts of 1 star and 2 star characters into Rare Souls, the rarer Gunners and Assassins are more often what people will be searching for as their collections are more and more complete.
Hell, even during this event, anyone farming for Immortal Soul Fragments has probably walked away with a ton of common Souls... which when used in bulk and the fodder sacrificed will turn into many Rare Souls. As such, it's easy to see why players of all levels are going to fill our the Warrior/Magus/Sentinel parts of their collection much quicker than Gunner/Assassin parts.
Even if you don't value Gunner/Assassin souls as much right now, at some point you'll probably find that there's far more from them that you want than from the regular souls, so we expect that yes, even one Rare Gun/Assassin Soul will mean far more than 10 Rare Souls (assuming you're trying to complete your collection of characters). No amount of Rare Souls will help you get something like a Gunner Corrupt Rescuer, or a Prisoner, or an Aces High Eddie... unless the fodder from those lets you get Rare Gun/Assassin Souls from sacrifice. The the only exceptions are event souls (which obviously are not always around) and Legendary Souls, which still are very likely to give you non-Gunner, non-Assassin characters.
tl;dr Rare Souls have a 0% chance of directly giving you a Gunner or Assassin, and as a collection of characters approaches completion, those are almost certainly most or all of what's left to find, and thus the value proposition changes over time.