In practice, its neither, and more akin to Sauron, the Necromancer or Shelob, Child of Ungoliant (which we have a deck tech for, by the way)
A circle means its a common card, its generally far less valuable as its a lot more common to find
For two mana (cast and equip), this sword gives the equipped creature +1/+1
You may include cards that have rules text that overrides this restriction or state that you may (or must) play multiple copies at the same time up to the number of cards indicated in the cards rules text
If some other effect gives you permission to cast Boltfire from exile, such as if you exiled it with Dark-Dweller Oracle, you may cast Boltfire using either permission
Sometimes supposedly overpowered cards end up being a bust