Agility

[Bear]

Looking at how fighting hero abilities (Might, Agility, Arcane Power, Constitution) changed in CoM. Most of them didn't change. Might, Arcane Power, and Constitution effectively doubles the growth rate of corresponding ability and corresponding super ability improves the skill x2.5 faster. Whereas Agility now changes shield growth rating from 2/9 to 11/9 which is x5.5 improvement and super Agility gives x7.5. Сomparing to x3.25 and x4.25 multipliers in original game that makes Agility an extremely beneficial hero ability. Much more valuable than in original game.
I understand rationale under slowing down hero shield growth with level. However, to make this change consistent I suggest to proportionally cut the rate of Agility contribution to leveling.

[Seravy]

Yes, I have been considering that but ended up not doing it because there are so many ways to raise defense it wouldn't achieve much and the others can't be reduced.
Defense growth was reduced because starting defense got raised by 2. I didn't bother to do the same on attack because it's not relevant enough (9 growth would go down to 7 to reflect the 2 increase of starting attack, who cares? 7 is hard to implement, too). I didn't reduce it as a part of a global defense reduction. (In fact I'm unsure if the current items have more or less defense than the original, I did reduce a few but there is a good chance by then it was already increased. To begin with the +2 from Plates never worked in the original.)
I did what you expect for resistance though - reduced starting, growth, items and the ability (Prayermaster). But resistance has a different game mechanic, the first points matter most and it becomes irrelevant soon enough so reducing all sources works well. Individual sources remain valuable. It also has only one type, resistance itself. Defense on the other hand the first and last points don't matter much but the middle points do so reduction would make individual sources of it worthless. Furthermore there are a ton of external sources that aren't defense but have the same effect of damage reduction and stack with it : Blur, Invisibility, Invulnerability, bonuses for To Def. Finally, while it's far from universal, the game does have a lot of ways to ignore defense (doom, illusion and lighting damage, resistance or other special type spells) and if anything, I believe introducing more of those could work better, not that I have any such plans right now (or free spell slots or ideas of that kind).