Berserk glitch/bug.

but it really does the dmg? or just show the numbers

because i remember power guard had that glitch, that the fighter/page was unable to saw the real dmg taken, but the other player could see you getting a 3487193085194 dmg instead

I think there are two damage numbers being calculated. The damage you do is calculated via client .exe in order to preserve real-time continuity with what we see and do, but the server takes care of the actual damage reduction of the monsters being attacked (this is probably why we can't see our damage with Heaven's Hammer). The server also informs anybody else in the region about the damage we do or take, so the server's number is shown for other people. Theoretically both numbers should be the same.