I think it'd be pretty cool if Skyburners penetrated through Heir Apparent's shield
It'd be a fun interaction. Attention to detail kinda thing. Yeah I know the perk says "Phalanx Shields" but that doesn't really matter.
Edit: People are commenting about balance, this isn't about balance. It doesn't matter Heir is getting nerfed, it's about flavor and paying attention to detail. Skyburner's needs a bit of a rework anyways regarding it's ability to penetrate phalanx shields, extra cabal damage. It could use the ability to pierce all cabal shields regardless of element, could probably lump in the proving grounds bubble too, actually give it a use for something