Thank you for the explanation. I think the best choices you can make is to honestly ask yourself what would you love to play. And for those sources for various boosts of the characters just to ask what are the benefits and what do you expect from such a solution - does it have some interaction with gameplay, storyline, forces the player to play a certain way (your system looks like that it forces to do an exploration as the crystals are found through it)?

I also think that great resource for "what to do with numbers" when designing a game system are pen a paper rpgs. (D20, GURPS, Shadowrun...). I believe it would not be a wasted time to try some, if not the game system it self then tons of little details and assets creating the atmosphere and immersion could be inspiring.

Maybe something for the melee game system as KISS should be applied:
apart from damage for the weapons you might have cogency or weight property on it (the higher quality weapons would have higher ratio of damage/weight)
this weight property could be compared with the wielders strenght and for example:

strenght < 0.5*weight = weapon cannot be used

0.5*weight<strenght<1*weight = weapon can be used with penalty equals missing strenght to weight into attack rating (attack rating if you can hit and damage what is the impact)

1*weight<strenght<1.25*weight = weapon can be used with no modificators

1.25*weight<strenght<1.5*weight =weapon can be used, with bonuses to atack rating of 0.33*(strenght-(1.25*weight))

1.5*weight<strenght<2*weight = weapon can be used, with bonuses to atack rating of 0.33*(.25*weight) plus 0.5*(strenght-(1.5weight))

etc.

Goal is to motivate player to make his choice of weapon for a given foe. For those who are swift and quick on their feets players might want lighter weapon to improve their chance to hit. Strenght also can be classically involved in rising damage done like WeaponDmg + Strenght/X = damage done.



Good luck

PM coming your way regarding music and sound