-Definition: "should" just means I think it would be nice

Stagger/Fall/Flung
Huge creatures should have a chance to fling you some distance with their melee attacks (e.g. Sauron LotR prelude style). Generally, I think the combat would feel exciting if you had a chance to have the following status effects applied, from least impactful to most: nothing, stagger (prevents attack for short time), fall (self explanatory), and flung (this would only apply to huge creatures). The chance of receiving the less-impactful effects would increase based on your general 'tankiness' (I would be curious to know how to define tankiness exactly) or 'agility' (again, however that is defined). This means mages have even more incentive to keep their distance, while tanks and rogues have to consider the costs of these effets.
Movement Slowing
Sidestepping and moving backward should have a movement penalty in general (maybe 40% for sidestepping, and 20% for moving backwards - this might already exist?). I think this would add a lot to the aesthetic of running for your life in a caravan raid or combat in general.
Similarly, mages should have further movement penalty when preparing and casting spells (60% overall reduction might even make sense). The whole "run around full speed while perfectly aiming your bow/casting a spell" seems too floaty to me and doesn't promote strategic positioning. This might also apply for some melee or ranged combat (definitely archers).
That's all I can think of right now! Thanks for the read.