The Blessing of Light is something that is intentionally left pretty vague by the story, probably as another way to let the player fill in the gaps with whatever they want, and while sometimes this manifests in the story treating the blessing like a bodysuit of kevlar, I think the much more interesting interpretation is to go full whump with it and establish that the only rule is that the warrior of light cannot die. Aside from the subplot in post-ARR/HW being more interesting with the real threat of death now upon them, it just adds so much sauce. We can magick away the possibility of their head getting chopped off with the superhuman reflexes Hydaelyn hath granted, and so it is very delicious to imagine someone who, rather than being unable to be meaningfully injured, is instead able to just keep going despite catastrophic bodily harm. The warrior of light just keeps fucking going, no matter how much they may wish they were dead. More blood than humanly possible spilling out onto the ground, face pale, hands shaking, still moving with eerie grace and agility, screaming with pain every time they bring another desperate strike down? Thats the good shit.
I recall the devs saying that party wipes in a dungeon are just the WoL having Echo visions on what Not to fucking do, implying that they hallucinate their death repeatedly before triumphing.
Which is equally, "That's rough buddy."
A young WoL preemptively seeing themself get incinerated by Ifrit.
