So I came up with a small list of suggestions - which stats and modifiers are needed, and how these different stats or modifiers should make a difference in a fight. Since we are not limited by some PnP game, we can make everything as complicated as needed. Please note that "length" and "weight" of weapons are rough approximations - it would do fine if all long swords of the same material were approximated as being the same length and weight, regardless of in- game representation.
- Strength – A stat reflecting the strength of the character.
- Dexterity – A measure of hand- eye coordination.
- Skill (Accuracy) – How well the character knows how to fight. Probably a number which increases with levels, perhaps you also need to specifically allocate skill points to increase this.
- Attack speed – Same as the above. Maybe the starting attack speed is weakly proportionally influenced by dexterity? This number might also be level-independent, as in for example Arcanum and Fallout.
- Bonus/ malus to Strength - Longer weapons you swing in an arc should give a bonus to Strength. D&D actually models this as weapons having different “dice” of damage, instead of having a base amount of player damage which is modified by the weapon.
- Bonus/ malus to Dexterity – Larger, heavier weapons are less maneuverable and should give a malus to dexterity. It’s best not to have minimum requirements for weapons and instead let the player’s calculated Dexterity with the weapon suffer by the amount of Strength they lack compared to the ideal Strength required for the weapon (which in turn is based on the weight of the weapon).
- Bonus/ malus to attack speed – Possibly same as above. Typically, lighter piercing weapons take shorter time of executing an attack with than heavier swinging weapons. I admit this is perhaps most often just a tiny difference.
- Slashing/Piercing/Crushing – This part should be pretty obvious (axes are not crushing weapons, and so on). Some weapons could have different kinds of damage at different distances. A large two- handed sword should be impossible to swing perfectly at a close enemy, but you can still deliver a pommel blow. Here, you also apply a proportional modifier which depends on how sharp/pointy/hard the weapon in question is.
- Optimal distance of striking, or “threat radius” – Longer weapons usually are good at a certain distance, but worthless against a simple dagger if you’re right next to each other. If a dagger- wielding warrior charges a Zweihander- wielding warrior, the latter would be able to have a (quite possibly deadly) “free strike” at the former. In the situation where two people fight with swords of equal length, this would not occur. A player with a long weapon should receive a bonus to attack speed when striking enemies who do not have the player inside their threat radius, since they have no need to think of their own defense (this is one reason why spears were used, and why they were used in formations IRL).
- Ability to parry/ dodge – Possibly proportional to the length of the "parrying end" of the weapon, weapon skill and Dexterity calculated for the weapon in question.
- Ability to avoid being parried/dodged – Like the above, but instead inversely proportional to weapon length (or generally, weapon size).