how so you merge mods.
The question is simple, the answer is not. I will keep it short
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get the sources for the mods you want to merge, at a minimum that means extract the .arz files, maybe the .arc files if they have .arc files with the same name
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figure out which .dbr files exist in both mods and then determine what the differences between them and vanilla GD are (i.e. what the mods changed) and then combine those changes in one .dbr file
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figure out if there are any overlaps in the .arc files and if so, if both mods contain the same file (in which case nothing needs to be done about it) - if something needs to be done here, chances are you need the actual sources, not just the extracted .arc files, unless these are some bitmaps only, in which case you need to make sure they no longer overlap and adjust the reference to them in the .dbr files
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build the .arz anew, if you extracted the .arc also build those
If this is not sufficient, familiarize yourself with the mod tools and WinMerge 
well looks like i wont be merging them then lol
up to you, it might sound worse than it is. Depending on what you want to merge there might be little to no overlap at all. So it becomes an exercise in unpacking and repackaging the files (which is unavoidable, as there is one .arz per mod).
well i wanted to merge smash and grab with grimarrilion for the 5 points per lvl and the better drops but meh
To be honest with grimmest in Grimarillion you get so much loot you don’t really need anything like that. With so many heroes spawning you level pretty quickly as well, even if actual progress through the game is slower.
As medea said, the drops are not that important. I have no idea how the mod does it, if it changes the loot tables, that will require some effort to merge, if it is more a global chance that was changed, it only takes a minute to merge, same for the points per level, that will only take a few minutes.
I wanted to merge Mods in the same manner as OP did, but found the compromise of utilizing console commands for the early game Skill Points, and roughly by the beginning of Act 2 I could turn on heroes spawn real high, so that loot and exp were not an issue.
The “disadvantage” of getting a lot of reputation in comparison to Smash’n’Grab is there. But otherwise, I think Grimarillion by itself has potential for much higher and easier drops than that mod. Skill Points and Divination Points can be offset by Console Commands, if that’s what you wanted to use it for.
That also would be the part that you can merge in with a few minutes of effort however, so if you focus on that part, the merge will be easy