In that if you want to use Martyrdom, you have to take out the nade before going down. With the nade out, you can’t fire any weapons, and it requires you to anticipate an inevitable death and prepare for it. To use, just press E (or whatever you have bound to Ability2), and Nader will sheathe her weapons to hold a live grenade in her hand. It’s not on a fuse, but you don’t get to throw it. At any point up to death, you can switch back to any of your weapons…
…but once you fall with nade in hand, there’s no chance of being revived. It’ll be exactly like Martyrdom as it is currently, except if you died without nade in hand, you can’t take it out, and if you had it in hand, you can’t back out of it.
Making Martyrdom use one of the nades in Nader’s inventory is another change I’ve seen tossed around; I think that’s a good idea, but not absolutely necessary. We’d have to see how that plays out in concert with this change.