We need some way to mark the IV's of units in game

Well you do have 8 options for favorites - You can use 6 to mark boons and Neutral status. Sure you may wonder what the bane is later on, but you're half way there!

I totally agree. How hard would it be for them to let us add a plus or minus sign next to a stat on the unit's stat page? The favorites option, IMO, is totally inadequate for this task, not to mention there are other things a lot of us want to use that for.

Totally agree. Wish they would come marked. May be worthy of writing IS.

Some units in the game even have a visualized boon when they are at lvl40. I think it's Sothe and Tharja's HP boon, LA.Hector's DEF boon and NY.Camilla's SPD boon. It's just a simple green number. The fact that the devs clearly have the ability to highlight boons and that they just don't want to do it for some reason, baffles me.

Use the favorite system to mark levels of progress and/or satisfaction, not to input where your two cents can usually discern (for instance, a marked Reinhardt will presumably do Reinhardt things). My system is currently 1) "Cursory", 2) "IV-L/M", 3) "Vs-IV-L/M", 4) "Final/M", 5) "V-IV/L+M", 6) "IV/L", 7) "Utility", 8) "Hold".

Groupings before a slash indicate categories, letters after indicate tasks. 'M' = merge. 'V' = variants, it means I have all the IV variants of a unit I want, and can merge additional copies willy-nilly.

One thing I have to correct is that I have no classification for skill construction.