Anyone trying to solve this should think about how the solution would interact with talents like Missile Weapons and Alertness, which effectively improve, respectively, a missile DX subattribute of DX and a perception IQ subattribute of IQ.
The way it works in most TFT PBEM games is that anyone can buy +3 to a subattribute instead of 1 normal attribute. The subattribute is more or less anything the attribute can do which isn't the attribute's main job. So extra talents becomes a special case of a broader system. This system isn't perfect but it works pretty well in my experience.
A suggested list of subattributes (much larger than in those games, you might not want all of them) might be:
- ST subattributes:
- Feats of strength (bend bars, lift heavy things, etc.)
- Endurance (resist poison, hit points?, etc.)
- Not weapon damage, which is notionally the main job of ST.
- DX subattributes:
- Missile Weapons (replaces the talent)
- Lightfoot (dodge traps, etc.)
- Nimble-fingered (thief stuff)
- Not melee weapon to hit rolls, which is notionally the main job of DX.
- IQ subattributes:
- Perception (replaces Alertness)
- Memory (for number of talents and spells, can be taken multiple times)
- Willpower (resist rolls, etc.)
- Not IQ requirements for talents and spells, which is notionally the main job of ST.