The tricky part is making the animations work properly, both weapon and auto attack animations. When creating the transmog system they probably didnt even have a thought that Artifacts would be a thing later on or people would want to DW over a 2h.
Mastery is boring but what it could be is a who knows but right now, it only applies to frost damage. If Plague Strike comes back, which people would probably ignore for the ease, it would be another thing not on its list. I would say to have the more mastery, the more frequent KM procs instead of having it based off of crits and have it give a crit. Mastery increasing the chance at gaining km procs could be an option, but then you would probably be looking to getting a certain % and ignoring it. The spec might need a complete overhaul for a different mastery to be introduced. There isnt much in terms of base mechanics to really build upon. KM for oblit and Frostscythe, Rime for HB and that is about it now.
I would like to see KM, since its basically just for one ability now, to give armor pen, possibly mastery could increase its armor pen as well as frost damage. Just so it scales with it? Not a groundbreaking idea but its something. Anything over 100% armor pen could be added into increase its damage after that but I think that might be just too much going on in terms of what mastery would do and everything going into making that change.
Its kind of complicated when you start delving into the mastery and the kit and trying to make it interesting or trying to work obliterate in it as well.
Mastery right now applies to everything except Obliterate kind of getting to the point of, just remove it if its that much of a detriment. Or, Inexorable assualt (BFA version) is baseline and does it on every cast of obliterate, doesnt stack, and does an additional I dont know, 80% attack power as Frost. It wouldnt be one major hit, but it would at least be doing some damage again.
The issue is it is physical damage while the rest of the spec is frost and when that is the case no matter what, when you start getting mastery if thats your best stat everything is going to outscale it.
Change Frostscythe to replace Obliterate for cleave situations, bring down how much damage it does to that of below Obliterate so it doesnt overtake it in single target scenarios, take away the crit multiplier and run with it.
There is actually quite a bit to go through when you dive into it and start trying to reduce or minimize the problems within the spec.
Downtime has been one of the biggest things mentioned since WoD when this “juggernaut” fantasy came out. It was mentioned in Legion and the artifact took care of a lot of it, and then BFA hit and it was all just “poof” gone.