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For Limited Weapon/XX - Silent Old Sanctuary Runs, collecting a Candy Box and selecting Arma Dio for another Passive works for the player if they didn't want to ruin their build. However the option disappears if you collect another Candy Box, forcing the player to either get a new weapon or 'skip' the rare pickup altogether. Is this a bug or is this by design?
storm crest
I can't speak as to whether or not it's a bug, but it's been this way for a while. If you get an arma dio one time from any source, it will no longer show up in the candy box or in random level up choices. Collecting them from the level up/candy box does not diminish the amount you can get from the darkana, but picking them up from the ground will prevent them from appearing in the candy box/ level up menu, so you might want to hold off as long as possible to get that extra one from the level up first, although I don't believe it's worth doing so.
I believe you can get an unlimited amount of either selector very rarely through the random events. The gold fingers also seem to give them as a cosmic or demonic reward, and I don't know if there are any limits on it that way.
What I do is make sure I get a greatest jubilee and clover, and I usually have no problem collecting every passive weapon that way, and as many active weapons as my computer can handle.
Protip: Banish the greatest jubilee just before rank 9 to make the game run smoother on limit break/egg/paranormal runs.