I don't recall whether I said it when it was released, but my feeling is that any profession that has a Spell Circle named after them, should have access to Arcane Blast.
To include, specifically, the Monks and the Rangers and the Paladins and the Bards.

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Failing that, is there a way--Treasure Trinket, SimuCoin Store, or Alchemy Anomaly--to provide access to that spell on a limited basis? (6-use 30-minute charm, or 30-day potion, say...)

I can get behind that, even I won't agree with it. :)

(Although I'll note that changing to three Attack Skill setups [one for Weapons, one for Aimed Spells, and one for Warding Spells], as I've suggested several times, would allow for precision in design...)

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Then, any possibility of such creations as in my second bullet point? Treasure drop, Store, or Alchemy?

I'm thinking in a "use warding spells" sort of way, which makes bolting wands such as those quite a bit less desirable.

(Also the whole "needing to train in another skill", since Aimed Spells skill is required to try and actually hit something. Warding 'just happens' from level and stats.)

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"All Pures (Wizards, Clerics, Empaths, Sorcerers, and Savants) will have innate knowledge of this spell" -- Estild's announcement

Fine.

Can the semis have NON-innate knowledge of the spell, and be able to train it? (That is to say, spend one [1] Spell Research to learn 1700.)

Wands lose out to Arcane Blast, because ammunition. (Both 'weight' and the 'running out' factor.) 0 mana that has a time cost beats that going away.

Wands also cannot trigger a runestaff, unless I'm mis-informed.

Could be... :)