Hmm, i think it is actually giving the berserker bonus, just not as much.
Whips depending on Dx: prolly accounts for it. Here is test nuttiness:
on a St:30 Dx:13 troll ranger:
a +1, 1d4+2 orc dagger yields +40, 1d4+25
a -4, 1d3+2 scourge yields +26, 1d3+13
EDIT: that was dual wielding dagger and scourge. single wielding each
yielded similar results, just less to-hit