1) Log in to any character with the full watcher weapon set.
2) Equip watcher weapons.
3) Find a 2nd player to help test, tank for private pvp is ideal or healer for pve.
4) Head to a zone with any monsters or a private pvp queue.
5) Enter combat and start a timer.
6) Observe what your stat level are at when you are at 5 stacks of the watcher set bonus.
7) Around 9m45s watch your stats closely because the bonus stats will vanish soon even though you still have 5 stacks of the watcher set bonus.
8) Please fix!
Observed Result:
The watcher weapon set loses its bonus stats around 10 minutes in combat.
Expected Result:
If you stay in combat the stats should never be removed. At least to a realistic time limit for the longest single target fight in the game (ToMM)
Video Proof:
https://youtu.be/MM7a1aBDe94