Concealed Weapon seems to proc Major Berserk from Major Gallop too wether i am in combat or not (or maybe it's Minor Expedition that i have from sloting Concealed Weapon).
tooltip : When you leave Sneak, invisibility, or cast Concealed Weapon while under the effects of Major Expedition while in combat, gain Major Berserk for 10 seconds, increasing your damage done by 10%.
If i understand correctly it is supposed to proc only while in combat and while under the effect of Major Expedition.
Major Berserk proc while standing still in town and casting Shadowy Disguise.
I made ticket no. 231229-001624 but its filed under "Feedback" and it got automatically closed.
My forum post has more detail.
on xbox|S