For Sakuya mode, I don't know if there should be different classifications for difficulties, or since being more niche be a side note, for the time on a run since weapons do different damage.

I've seen that difficulties in the board have weapon categories.

Each difficulty has its own set of weapons, so unless you can use a weapon set into another difficulty, there is no need to add those cases.

Furthermore, Normal and Hard also have different weapons:

Normal has single pistol + slow shotgun in its set Hard has akimbo pistol + fast shotgun in its set.