Me and Thomas had a little chat on IRC and agreed on the following things:
-With another class of weapons (We already have Advanced, Normal and Unique), Exotic would make 4. That's simply too many different weapon CLASSES for DoomRL. Advanced weapons get chucked out, as they're almost rarer then uniques and STILL need mods to make them useful. 2x the RNG for less Dakka.
-To keep Wizkid useful, it's upped to 3 Levels and each level grants more modslots on normal weapons (WK 1 gives 1 extra slot, WK 2 gives 2 extra slots on top of that, WK 3 gives 2/3 extra slots on top of THAT). Granted, you still need luck from the RNG to find the right mods. In addition, some weapons could have less mod slots (BFG, anyone?)
-Unique weapons get done over. They become less of the "HEY IF I GET THE RIGHT ONE THEN I WIN OTHERWISE I JUST GET IT NOTED IN MORTEM" and more of the "Hey, now THAT's useful. Not Gamebreaking, but useful.". This is achieved by:
--Making unique weapons more balanced around the board and remove the powerhouses. Staples such as the BFG10K and Dragonslayer can stay, but tone up/down things such as the Necroarmor, Nuclear BFG, ect. They're still better then your average weapon, but not totally gamebreaking.
--Making uniques more "different". Stuff such as the NPR/GCB is good. It's not like the Missile Launcher/Minigun, which is just your "Average weapon with 9001% more Dakka". They should be Unique, different from the norm. This leads to the removal of such things as the Minigun/Missile Launcher from the Unique list.
--Make uniques more versatile. For instance, take your GCB. It's got 3 fire modes, so it can be used on a Chaingun run OR a pistol run. It's one of the most versatile uniques out there. The Jackhammer should be affected by TH, so it can be used on a Chaingun run OR a Shotgun run. Stuff like that. (However, so the Jackhammer doesn't become the new iWin button, it gets fixed, as the first point)
Thomas says that Exotic weapons fill in the gap between these new uniques and standard weapons. I don't know much more, so i'll leave it up to him to explain.