Tairn's power

In Chapter 10, Theophanie says to Violet - "who chose you first? The one who gifted you the power of the sky, or the irid?"

At first I thought that "power of the sky" meant lightning. But violet isn't a lightning weilder. She wields pure power that just manifests as lightening. I'm assuming Theophanie knows this as she knew everything else about violet. She also knew Garricks second signet.

Did she imply then that Tairn draws power from the sky? The wording is too suspicious to mean regular lightening.

Could Tairn somehow be pulling magic from the sky? It could explain why he's so powerful.