What counts as an "arcane spellcaster"?

[Aricks]

Ring of Minor Arcana (https://2e.aonprd.com/Equipment.aspx?ID=478) and the Robe of the Archmagi (https://2e.aonprd.com/Equipment.aspx?ID=464) both mention being an "arcane spellcaster" as part of various requirements of the items, but after doing some digging it's unclear to me as to what that actually means. The two cases I thought of off the bat are:

1. Does it mean having the "Arcane Spellcasting" ability? Good for wizards and magus but tough luck for rune witches.

2. Does it just mean you can cast an arcane spell? Otherworldly Magic for elves and being an Arcane Wellspring gnome give arcane cantrips but use charisma instead of intelligence so less arcane-y than a wizard or magus, but still technically casting arcane spells.

I know the robe states "characters who can cast arcane spells" and seems to equate not having that ability as not being an "arcane spellcaster" but it's less clear for the ring.

Given the robe definition I'm leaning towards #2 but I'd like to hear others weigh in on it.

[Guntermench]

Either of those make sense, but I think it's just a spellcaster that uses the arcane tradition.

[Asethe]

An Arcane Spellcaster is someone with the Spellcaster class feature and uses the Arcane tradition, so Rune Witches would be fine.

While Innate Spells might allow you to cast an Arcane spell, they don't grant you the Spellcaster class feature.