Finally, the answer to that old question in cb .. (in General)

"The weapons you have selected to consume is more powerful than the one you chose to change. Why would you want to do that?"

.. have found the answer!

I tried to find the base damage a 20ST minion does with my 92x1+0 BoNE, which turns out to be 17 in average.

Then i wanted to do the same with the morg, but that's not x1 but x10 sadly .. so that's why i would want to do that ;)

and another cb quest solved:

BoNE 92x1: 17 base damage
Morgul Hammer 84x1: 13 base damage

Base Damage = 0,0573 * weapon_base / (1 - 0,0075 * weapon_base)

So total damage calculation formula is:

Damage (avg) = (0,0573 * weapon_base / (1 - 0,0075 * weapon_base)) * SQRT ( (ST/20) * Weapon_damage_multiplier )