Cool.. A Unison Raid that took so much power that it's almost put two of my characters out of the competition, and not a single opponent takes so much as a scratch. I get that some characters aren't allowed to be hurt, but come on.
Caits, I know it must be inconvenient to take into account how my character's magic works, but in the anime Nullification Magic can shut down even the attacks of Gildarts. Mundane Spark affects the magic signature of an individual. If it touched Penny's ethernano, it would shut down all of her magic for about a minute. What is this distinction you've drawn between fire magic and phoenix magic? Ignoring the fact that Mundane Spark nullifies all magic, they're not different. Immediately after her 'fire magic' dies out, she uses a big fire spell. Getting nullified wouldn't even be a problem since she spends the next minute having a touching moment with Merlina anyway.
Silicates like obsidian, which I'll go ahead and say the Tectonic Blades were made of, have a melting point of 1200 degrees Celsius, or 2192 degrees Fahrenheit. That's a little more than 1/6 the surface of the sun. That kind of heat is far more destructive and lethal than the Blades would be.
Regardless, what you wrote is dissonant to what Hatake wrote. Since you're GM, I assume your chain of events overwrites his.
A super easy solution would be to pull away from Nolan's attempt to help, take the Spark, fizzle out, and fall to talk to Merlina. However, given how well my suggestions in the past have gone, I won't hold my breath.
I can make it so that Nolan took a blow from one the blades. I wouldn't mind doing that.