Fiery Runes - Is action economy that powerful?

[gr8artist]

I came across the Fiery Runes (http://www.d20pfsrd.com/magic/all-spells/f/fiery-runes) spell while working on a build, and I was taken aback by how weak the spell seemed.
It's 2nd level, so comparable damage-dealers include Scorching Ray or Acid Arrow.

Scorching Ray deals 4d6 per ray, with 1 ray at levels 3, 7, and 11. Total damage: 4d6 - 12d6 fire

Acid Arrow deals 2d4 per round, for 1 round +1 round per 3 levels (3, 6, 9). Total damage 4d4 - 8d4 acid

Compare that to Fiery Runes, which deals 1d4+1 at levels 3, 5, 7, 9, and 11. Total damage 1d4+1 - 5d4+5 fire

Scorching ray can be split among multiple targets, while bot it and Acid Arrow can benefit from Critical Hits. Fiery Runes is not only melee-only, but targets a single creature and cannot Crit.
Scorching Ray and Acid Arrow are both normal attack spells, cast as a standard action during combat. Fiery Runes is a standard action to prepare, and then a swift action to discharge. Fiery Runes lasts long enough that it can be cast before the fight begins, effectively freeing up an action in combat.

So that's my question - Is that possible action economy buff valuable enough to warrant such a drastic drop in damage?

[Deophaun]

Eh...

But keep in mind, you don't have to cast it on your weapon. You could actually get a good alpha strike going if you spread it around to the rest of the party, assuming no one had anything better to do with their swift actions.

[Coidzor]

Honestly, Fiery Runes wouldn't feel too out of place as a buffing Cantrip if you changed it to +1d4 and took off the scaling.

[CasualViking]

Nah, it's a pretty bad spell. I can imagine it being marginally useful with some metamagic trickery to inflict conditions every time it does damage, or to kill trolls if you're too dumb to just chop them up and burn the twitching corpses, but I think in either of those situations I'd rather have Flaming Sphere.

[Kurald Galain]

So that's my question - Is that possible action economy buff valuable enough to warrant such a drastic drop in damage?

Actually, yes it is. Once you have reached the level that you have 2nd-level spell slots to spare, there's no reason not to cast it on your allies' weapons a couple times per day. The spell is pretty much guaranteed to connect, except against spell resistance.

It's still not a great spell, but it's basically a free 18 damage (plus boost from Evocation school, familiar, or bloodline). That's its strength: you don't use it instead of anything else, but in addition to anything else. So overall that's pretty good.