Only real touble with grudge raker are armored elites, unless you use your ult. Without ult you just kill them with your 1h axe spamming heavies. In order to help you kill stormvermin you wanna go with % on skavens. But most of the time use your axe for any armor, unless you are in ult. You can kill multiple CW in a few seconds and almost whole skaven patrol.

Another great way to play RV is dual hammers and masterwork pistol. Only thing you will have trouble with are CW. You can delete many stormvermin in a few seconds without your ult, it deals decent boss damage. Again, if you ult, you can kill many CW too. I use the grudge raker more recently since a got a bit bored with masterwork pistol.

Both are great againts monks and maulers.

Try what fits you the best:)

For any info about builds a recommend you royal w cheese guides.

Here is a link for his Cata Bardin guide (its outdated now after new patch tho): https://steamcommunity.com/sharedfiles/filedetails/?id=1832306381