As far as I know, the only mechanical thing Aim does in any version is set your base hit to 255 for that attack. Couldn't help you with recoding it (little experience with SNES assembly).
Making Regen heal MP instead of HP should just be a matter of tweaking one or two bytes, but making it run off of the user's stats would require some rewriting.
Hmm, looking at the FF4 Reference Book site, Aim just sets hit rate to 99%, so yeah you're right on the money there. It was supposed to also have Bow damage + Strength 1/4, but that only happens in FF4A (and the ds version I'd imagine as well).
Due to certain changes I've been making in my project (tying the Bows and Arrows indexes to 2 now-dummied weapons to allow the rest of the bows/arrows become new weapons), I cannot for the life of me get the Aim command to function properly.correctly. The main reason for this I believe is because Aim was only meant for bow & arrow, or the command checks that a character has some weapon in each hand.
Is there a way to allow it to function with a one-handed weapon? I tried messing with it's ranges in FF4kster, but to no avail. I'm not actually sure of the benefits Aim would have now that I nexed Bows/Arrows (I think all the command does is ensure a hit? I'm not sure what else it normally does)
I'm also wondering if it's feasible to tweak the Regen command to heal MP periodically instead of HP based off the Wisdom or Willpower stat. Seeing as Yang is the recipient of this command, I don't think it would be game-breakingly overpowered if I were to go this route.
Aim *should* be a simple range check which my information was put into the editor, I could have sworn we tested this out long ago... but I did just try it out and it didn't change anything. I still have notes regarding Aim's Range check in ASM, so let me find that fast...
Here we are, they're some of my older notes but should still be readable...
In ROM this is located at...
01A48E - C9 05 (Compare with Dark Wave's Command)
01A492 - C9 08 (Compare with Sing's Command)
01A496 - C9 0C (Compare with Aim's Command)
01A49A - C9 10 (Compare with Twin's Command)
01A4F8 - C9 61 (Right Handed - If the Weapon value is this or above this (or 00?) Dark Wave cannot be used)
01A504 - C9 61 (Left Handed - If the Weapon value is this or above this (or 00?) Dark Wave cannot be used (May be Equipped Hand)
01A50E - C9 44 (Right Handed - If the value is this or above this, Sing can be used)
01A512 - C9 4D (Right Handed - If the value is this or above this, Sing cannot be used)
01A51C - C9 44 (Left Handed - If the value is this or above this, Sing can be used)
01A520 - C9 4D (Left Handed - If the value is this or above this Sing cannot be used)
01A52A - C9 54 ( - If the value is this or above this Aim can be used.
01A52E - C9 61 (Right Handed - If the values it this or above this Aim cannot be used (Looking for Bow? This would hint that Aim can be used with two Arrows equipped or two bows... well I'll give it a shot... Yep. Looks like it's right. Aim can be used with Two Bows or Two Arrows. An interesting non-check. Good on the programmers.)
As for Regen... that was actually one of my first projects and I failed. I still think I'd fail if I looked at it now. You see the amount of healing it does to the player is through a very specific set of code which runs through into normal HP recovery. In the past I had a lot of trouble changing it, and in the end had no success. Making it based on Spirit or Will though was done for Combat Boost where it is based on the character's Will.
Based on your notes, it sounds like the command looks through the Bow and Arrow ranges, then checks that both hands have a weapon in them (combination of bow and arrow, bows, or arrows), then runs a check of the Aim ranges to set it's usability.
Though now that I've read up a bit more on the Aim command itself, I'm not too worried about losing access to it by essentially removing bows/arrows. Her accuracy doesn't change much at all now that her weapons don't have the penalties of bows or arrows, so perhaps I'd be better off adding it to my Gamebreakingly OP/Wasted space list alongside Boast, Cry, and Peep haha.
It's a shame Regen is set up the way it is. I was going to use that as a way to balance Yang's high-powered Wishes and his intentionally low MP, but now that I think about it, the low MP itself acts as more of a balancer since once it hits 0 those spells essentially become a failure chance for the couple no-cost skills also set. :) I'll just retweak Regen's message so it'll mention HP again instead of MP, since normal Regen still fits this Yang's character.
Making it based on Spirit or Will though was done for Combat Boost where it is based on the character's Will.
Oh yeah, I forgot Combat Boost did that! That's certainly a much better system than vanilla FF4's locked set rate.
We have EVEN MORE themes now, but some old ones are gone...