Is Spellfire effected by SR?

[eyebreaker7]

I've read a few things online about Spellfire but none of them say anything about whether it is or is not effected by Spell Resistance. Spellfire says it's raw magical energy. Being that it says "magical" I'm assuming SR WOULD be effective?
I'm trying to make a sword that deals extra damage kinda like Spellfire except it would be raw ARCANE energy not MAGICAL. I was thinking something life the Flamestrike spell but magical energy instead of the fire. It would be limited to the standard 1d6 extra damage as if it were a normal cold, fire or electric weapon. Not sure how I could go about making it though. How could you create it? I mean arcane energy is what mages use to make their spells right? So it would still be magical?
Or maybe make it kinda like a Rod of Absorption where it could absorb spells and then use that energy as additional melee damage?
Looking for ideas here how to make it.

[Psyren]

Despite the name, it is supernatural and thus ignores SR. FRCS:


Spellfire
...
Unlike most supernatural abilities, spellfire is affected by spells and magic items that affect spell-like abilities, such as a rod of absorption or a rod of negation (if pointed at the manifestation rather than the wielder). It can be thwarted or counterspelled by dispel magic, and theoretically a spellfire wielder could counterspell another's spellfire. However, spellfire is a supernatural ability and does not provoke an attack of opportunity when used, nor is it subject to spell resistance.

As noted above, it does have some weaknesses that other supernatural abilities usually don't, but susceptibility to SR isn't one of them.

[RNightstalker]

Homebrew a Spellfire & Spellfire Burst weapon enchantment?

A DM might let you use it on a spell storing weapon, a ring blade or ioun blade.