I was Weakened by a shade and then ran away and died from poison. There was a wandering healer right nearby so I ressed and started retrieving my items and then got the notice that my strength had returned to normal, about 20 seconds after I had already died and ressed.
Thanks for the report. There are actually a few bugs associated with this topic. Buffs/Debuffs do not currently "time-out" and wear off after their standard duration, if you are standing still. A weaken currently lasts forever, until you take a step and the system recognizes it as still in effect. Back on topic, a character's death should clear/nullify any existing beneficial & harmful blessings/curses. Reactive armor, Protection, & Magic Reflection should all be cleared upon death as well, none of which are currently working properly. These are all known issues, but probably won't see a patch correction until after the Beta has ended.