To test the iconic class (and because I'm a WF nut), I created a Bladeforged. As I got my Feats, Diehard was listed, which made me concerned so I took it out of necessity. However, I later Tested that I couldn't drown, and logged on with one of my WF characters, to check: she didn't have any indicator that WF have Diehard/ Inert Regeneration (not listed under Warforged Traits, though I know WF have it).
Hmmm...
I logged back onto the BF then, to respec out Diehard, in order to check if the character actually has it or not...I ended up heading out to Locania in the Marketplace for the Free Feat, rather than pick a bajillion fragments off the table necessary to make the Exceptional Siberys to appease Fred.
By doing so (I switched Diehard for Toughness btw), I got a message saying I had Enhancements dependent on Diehard (Defender of Siberys Prestige line), and thanks to the respec, I lost all of them (need to Re-enhance).
All to figure out if I fall to below zero hp and no monster coups me, if I will get up again.
It also means I've currently locked myself out of DoS unless I take Combat Mastery, Tower Shield or Shield Mastery...