My take, it's a special application of Haki, especially gor CoC. Maybe an advanced form of CoC that's focused on its nullification capability.
Everytime we see PoL in action as far as i remember is either to nullify a mental block (Sanji, Kuma), physical damage(Sanji) or DF abilities(Sanji, Garp), except for Sanji's flames, which could just be explained as the PoL variant for CoA.
I really hope it's Haki related, I'm not a fan of Oda introducing a new power system this late in the series, doesn't matter if he foreshadowed it since chapter one or whatever.