If i was to go with one of the solutions presented here I would say Hecate's would be the best. Since with winterclaws idea would need alot more processing, since it will need to process the calculation every x amount of minutes rather than just when the ability is cast. This is because a stat can change during the fight with a drain spell for example which would be unnessasary imo.

The reason the formula seems somewhat complicated is so the battle system is balanced, you dont really want someone who has base stats doing the same amount of healing as the person with a full Mnd build.

But as it stand I dont think it needs anything, you soon find out from use which skill does more damage, haymaker vs jarring strike. Skewer vs Moonrise. Cure vs Sacrifice etc. If it was all laid out on a plate where is the fun in discovery. I dont think too many people would like a map marker for chests for example it gets rid of the fun of exploration.