Necro down stat bugged?
Well, idk about the first 2 things you mentioned, but the third one is an important one.
Necros have a third of the downed health as everyone else in PvE/WvW for some indiscernible reason.
The tankiest necro will still be defeated after being downed faster than the glassiest ele/thief will.
Ok I see, so 1/3 of downed HP is probably why I never felt 1 or 2 were working, simply because I died too fast after I was downed. No wonder a random spider can 2-hit shot me after I was down. Thx for the tip~ :P