Personally I believe Plague Monks, and the like, should cause fear. They are giant rats, that are cutting themselves, foaming at there mouths, covered in there own crap and covered in unknown diseases. If I say a huge block of these running down the street one day towards me, I would probably crap myself and run as fast as I could. What do you think?

if i ever sall a skaven or s gisnt rat i sh*t myself and run downt the street

That's exactly what i'm talking about. Anyone would. I would run even if I had explosives with me. Most of the people in the game has a sword and shield.

If you gave them fear there points would sky rocket.
as fear is quite expensive.

What they should have is like a lan moulder build a monster laboratory.
if you take a moulder general then you can create one.
they could be created similar to deamon princes

nurgle warriors cause fear. Plague monks perhaps should... but if u see a rat covered in filth? Every knows about the skaven, and their cowardice, most ppl wouldnt be scary.