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As stated above, if I get hit whilst wearing the Fallen Hero set the explosion happens as normal, but then a glowing aura sits in the air where the explosion took place for some time until I either interact with it or let it expire.
Interacting with it envelops me in a glow similar to that of the aura, but I do not know what it does beyond that. The tooltips on the armor make no mention of this interaction, and I cannot find anything online.