Yet another interpretation could be that a figure with ironskin is immune to attacks that have the sorcery attribute. At least it's simple to apply. Although if this was the intent, why not include it in the "damage reduced to 0" section...
</braindump>, carry on.

It works well because sweep is rare and it would be odd for blast or breath to suffer from elevation effects due to the nature of them (which is more or less a thematic support, but its only support for 'feeling' comfortable with a necessary RAW interpretation where the rules are contradictory.
Not doing so bad, I'd say.