His ice makes frostbite. Invel and Gray need such feats to be proven right.
BTW, Kuzan has done the
same thing of freezing the air itself. The Partisan swords appear from nowhere and the ice Shirohige is encased on appears around him. He doesn't make contact with the ice nor the ground (see he's mid-air).
It wouldn't instantly kill Irene unless Kuzan encases her whole body into ice, but losing an arm or a leg will severely cripple her. Even her own weight can make that happen, as seen with Jozu's arm.
@Trinimac
Too bad for you we're scaling Doffy to Kuzan because of that, fam.
Some of the reasons why Doffy's case is weird it's because there's a fair amount of possibilities as why he broke free. Whether his Haki was strong enough to prevent getting encased on ice or his Ito Ito no Mi helped him to do it despite being clearly inferior to Kuzan. None of those are abilities Irene possess and as such she shouldn't be able to break free without her own feats.