I'm pretty sure even if they hide and come back several times it still takes the same number of shots to kill them.

: I don't have a problem with Hard Light itself. I don't think it's light made
: into a physical substance any more than I think that Halos once graced the
: heads of angels. It's figurative speech.

Well they put out stuff saying it appears (to UNSC scientists) to be photons contained in some kind of field or something...

: What I do have a problem with is the moronic way 343i used it in Halo 4.
: Prometheans are made out of it, guns fire it, Forerunner weapons convert
: enemies into raw hardlight, the energy sword is now made out of it...

and the last I knew (during the lead-up to Halo 4) the energy sword is still plasma in a magnetic field, and since that's what seems to make the most sense for something like "hard light" to be and they never described it that way, I'm going going to say it's unrealistic.
Weren't there large objects and structures and even whole buildings made of it in the books (the new books)?