Played a lot Nader the other day.
Regarding Martyrdom: I think it is a pretty fun feature. It takes some time to get a grip of it and also some decent luck, but it is totally worth it. Very satisfying. See screenshot 
Regarding the nade launcher: after playing some time with it I was struck by a nostalgic feeling of pwning people with a Quake1 pineapple launcher. Once gotten used to it, it releases a brutal massacre in close range. Still it is not perfect yet. To get to Q1 satisfaction level, the arch of grenades must be corrected (hard to say which way, perhaps a more straight arch rather than currently a bit bent arch). Also the delay after firing must be reduced because currently the weapon is not as responsive as one expects it, resulting often in launching a nade to a spot where an enemy was 0,5 sec before.
All of this results at the moment in Nader being pretty weak and vulnerable, while relying on luck most of the time. If in close combat Nader can still hold her own to certain extent, at long range she is a dead meat, that’s for sure. Her secondary weapon must be buffed somewhat in order to make this character generally viable.
IMO Nader is a valid character that has a lot of potential that deserves its place in DB, but needs some tweaking which isn’t a surprise of course.
Another option for tweaking Nader could be turning her into a QWTF Demoman, by providing her with an ability to lay pipetrap from the same grenade launcher. perhaps one ability button could switch the type of nades fired from pineapples to pipebombs, while another ability button (or USE button( could activate the pipetrap detonation on the floor. The single pipebomb launch into the air followed by detonation of it while still in the air could work as infamous fireworks weapon, which takes some skill to use in order to kill enemy by carefully timed pipe explosions near his face. That would allow Nader to be a more defensively oriented class in order to deny some choke points, without simple nade spam as now. She could then help build some stationary defense lines around, as she would guard certain known areas and require medic and fieldops assistance regularly, which would make defense more strategic than now.