User blog comment:Andre5913/Lore-wise Champions Power Tier list/@comment-8050014-20140221134122/@comment-24268958-20140221181608

I'll elboarte here. Irelia almost died during the Noxian invasion of Ionia, but the mortal Soraka came to help her. The only way she could save Irelia was by binding her life force to her Hiten Blades, which revitalised her, and gave her greater mastery of the Hiten Style.

Essentially the thing to note here is with her life force being bound to her blade, it serves the same function as a Phylactery, the item which Liches use to contain their souls so that, should their body die, they can still continue to exist. If the blades break, she dies. Her death animation involves the blade stabbing her, which would essentially be permanent death, provided the fields of justice weren't a magical simulation.

Hope that explained it decently enough.