This mod includes several damage calculation tweaks to keep vanilla mechanics to up state with modded gamestyle:

Non-Combat Damage/Healing Scaling

This mechanics scales the several damage types with entity max health, but it would not down-scale damage for entities with low max health.

For example, Drowning by default is scaled to 2% of entity max health. Vanilla drowning damage is 2.

For entities with 200 max health, they will take 2 * 2% * 200 = 8 damage every second.
For entities with 30 max health, since 2% * 30 < 1, they will still take 2 damage.

The default configuration has:

Starvation, Cramming, Suffocation, Drowning, withering, thorn: 2% max health
Fall: default off
Poison: 5% of current health
Regeneration effect, Natural Healing: 5% max health

Fixed Bonus to Percentage Bonus

There are several enchantments and effects that gives player a fixed addition bonus. This mechanics change them to percentage instead. Numbers can be adjusted in config.

Sharpness Enchantment: +6% damage per level
Smite-like Enchantments: +12% damage per level
Strength effect: +30% damage per level

Linear Reduction to Exponential Reduction

The protection enchantments and resistance effect are stacking linearly in vanilla. This makes the first few levels too weak and the last few levels too strong. This mechanics change them to stack multiplicatively, so every levels have the same strength.

Protection Enchantments: -4% damage per point (x96%)
Resistance Effect: -20% damage per level (x80%)

Resistance I provides -20% (x0.8) damage reduction, and Resistance IV provides -80% (x0.2) damage reduction in vanilla. This means the first level reduce damage by 20% and the 4th level reduce damage by 50% compared to previous level. In the new calculation, Resistance III gives -48.8% (x0.512) reduction, and Resistance IV gices -59.04% (x0.4096) reduction, which means from III to IV it further reduce damage taken by 20%.

In vanilla, each protection-like enchantments adds protection points. regular protection adds 1 per level, fire/projectile/explosion protection adds 2 per level, and feather falling adds 3 per level. Each protection point gives -4% damage reduction, capped at -80%. With this mechanics, new damage becomes (1-4%)^points, which means at 1 point it's same as vanilla, but at 20 points it's -55.8% (x0.442) compared to -80% in vanilla.

Miscellaneous

This mod also adds the following small QoL mechanics:

Attack breaks grass and then still hits target (default: on)
Use sword to block attacks like shields (default: on)
Play arrow-hit sound when arrow hits target (default: on)
Hide flame effect when player is on fire but has fire resistance effect (default: on)
Disable falling attack (default: off)