This isn't meant as an official response, just a commentary re: mid-ranked Ragers.

I don't think DB is a balancing factor for ABS during the mid-ranks. I think DB and Resist (not so much spellbane) are balancing factors during the mid-ranks for (1) leveling without access to magic/communes (no protections/healing), and (2) low moves and lack of refresh. In the midranks, a RBW plays out kind of like how one historical writer described Crusader Knight running up against Muslim calvary - basically you had one powerful shot without much opportunity for reload. Midranked RBWs are very powerful, but the weaknesses (mainly movement) are exploitable by enemies that either want to avoid them or string them out to trap them. As Malakhi I didn't get my Rager weaknesses exploited very often even though I fought a lot of people outside the "rager box", but as a Rager enemy (mainly imperials) I have exploited Rager weaknesses with IMO a good rate of success. I have also failed miserably when I opted not to exploit a RBW weakness (e.g., fight a RBW 1v1 at the village gates - which is the best case scenario for the midranked RBW when you think about it). Anyway, that's where I see most of the balancing considerations.

Setting that aside and looking at DB vs. available protections (ABS), I think it is worth noting that DB already scales with levels, meaning it implicitly factors availability of protections into account.