First off (as more of a point of interest really), Cure V and VI actually have a hard cap (I believe this was tested with a Primeval Brew). If you are interested, my source says they cap at:

Cure V
810 HP / 1215 HP

That implies a hard power cap of 1240. Adding that to my spreadsheet for personal reference.

After doing some re-writing to clean things up, I found that values that make the scaling on the lesser cures make sense. The overall pattern being used is much clearer now.

The current cures (aside from 6, though 6 is still similar to the others) follow fairly distinct patterns. It's clear that the design for the formulas is a mixture of power (value generated from skill/mnd/vit) and the amount that each spell cures (which how the caps get defined).

Cure 1 has a minimum cure amount of 10 HP, and increases by 10 HP per cap. Cure 2 has a minimum cure amount of 60 HP, and increases by 15 HP per cap. Etc. See table:

Code:
        Min Cured     Cure @Cap1    Cure @Cap2    Cure @Max     Interval
Cure 1         10             20            30           40           10
Cure 2         60             75            90          105           15
Cure 3        130            160           190          220           30
Cure 4        270            330           390          450           60
Cure 5        450            570           690          810          120
Cure 6        660            960          1140         1140          300~

The amount of power required to reach those caps depends on a base value and the rate of increase the devs decided on. For example, Cure 3 has a base value of 70 and a rate of 4 (for up to Cap 1). To get from 70 to 160 HP cured at a rate of 2 power per HP means you need 90*2 = 180 power. To reach the next cap (30 more HP) at a rate of 4 power per HP means you need another 120 power on top of that. And so on.

Ultimately, everything is built around the intervals between each cap (generally doubling with each cure tier), and the maximum allowed power (1240).

The maximum allowed power is why the lower tier spells suck past a certain point. Cure 1, for example, reaches cap 2 at 100 power, and has an interval of 10 HP cured per cap. That means going from 100 power to the max 1240 power only increases the total amount cured by another 10 HP (1 HP every 114 power).

Cure 5, on the other hand, reaches Cap 2 at 560 power, and has an interval of 120. That means it improves by another 120 HP cured with an increase of (1240-560) = 680 power, or 1 HP every 5.67 power (about 2 points of mnd).

Cure 6 caps early because the absolute maximum power allowed (1240) hampers it (it hits the max power before it hits its natural cap).


Because of the way they've built it (now that I have a pretty complete picture of things), I can see how they might be hesitant to change it. For example, I don't know why the specific value of 1240 is used as a max power, but if it's hardcoded into various places, or there's other code that depends on that particular value, it could be very troublesome to change (and easily break stuff if they don't go through everything very carefully).

Likewise, they've built their cure tiers with progressively doubling intervals (though they didn't use 240 for Cure 6 for some reason). A large part of the balance of the game is the progression of damage taken vs damage healed. They have a 'nice' pattern for how healing improves, which, if they change, could throw the overall balance out of whack.

At this point I'm doing some rethinking of my proposed revisions based on these limitations (ie: min cured, 3 defined caps, max of 1240 power).