The power of an Archivist is extremely dependent upon the DM. If he only allows you to walk in to a shop and buy scrolls that appear on
these tables, you're going to be pretty OK. If he allows scrolls of spells from other books, you're going to be great. If he allows things like
Divine Bard to get divine scrolls of Bard spells, or Sword of the Arcane Order to get divine scrolls of Wizard spells, you're going to be fantastic.
Technically, an Artificer has access to*:
- Any Cleric, Druid, Ranger, Paladin, Adept, Healer, Shaman, or Shugenja spell
- Any Domain spell
- Any Bard spell (via the Divine Bard varian)
- Any Divination, Necromancy, or Abjuration spell from the Sorc/Wiz list (via Divine Magician ACF)
- Any Wizard spell of 4th level or below(via Sword of the Arcane Order)
- Any Sorc/Wiz spell of 6th level or below via the Favored Soul of Bahamut ACF
- Any Sorc/Wiz spell of any level, via Hexer or possibly the Southern Magician or Alternate Spell Source feats
- Any spell of any level from any list, via a scroll made by a 12th level Warlock
- Various other spells, via certain Initiate feats or prestige classes that add spells to your list
Also, remember that you can cherry pick which version of a spell to learn. For instance, Lesser Restoration is a 2nd level Cleric or Druid spell, but a 1st level Paladin spell, which means an Archivist can get it as a 1st level spell.
The big question is, how many of those tactics are going to be allowed? If the DM severely limits your access to scrolls, you might wish you'd been a Cleric after all.
*Some of these tactics are debatable, especially the Warlock one or the Hexer/Southern Magician/Alternate Spell Source one.