

My Knight in Falling Armor: A Hater of Superhero Landings
A tweak meant to introduce extra moments of "oh yeah, that makes sense" without needing a tutorial. Very modpack friendly!
The premise: increasing the overall "weight" of one's armor increases the amount of fall damage they take. By the default configuration, this means taking roughly 3x the normal amount of fall damage when wearing full netherite armor. Note that this isn't "felt" until the player starts falling from more significant heights--I swear it sounds worse than what the actual gameplay entails, haha.
This behavior also affects vanilla mobs that can equip armor (configurable) and horses. The extent to which they're affected can be changed in the config.
Note: This mod does Not decrease player speed. Decided against it because it feels like a constant penalty, whereas fall damage is something that can largely be prevented with additional caution or strategic armor use. I may add a speed multiplier as a configurable option in the future, but it'd definitely be off by default.
Tags:
There are four different weight classes that are used by default: light_armor, medium_armor, heavy_armor, and very_heavy_armor.
I've put in an additional "extra_armor" tag that can be used how a modpack maker sees fit. Since all the class weights are configurable, all five classes can really be used in any capacities depending on your imagination. Modpack/datapack makers that want to change what's in these default tags should remember to replace the items already present in order to correctly override them!
Note that these are largely meant to respect design principles rather than realism. Gold armor having additional disadvantages because it's extremely heavy irl seemed egregious, and diamond armor being as light as leather felt equally wrong.
In addition, to add a little more versatility without even more tag bloat--putting one armor item in more than one class makes its weight the average of all the tags it's put into. This is why chainmail armor (by default) is in between light and medium, for instance.
You can check the default configuration of tags out here.
Configuration:
All values can be configured! It's a little overwhelming, actually. Sorry about that.
There are two types of equations that can be chosen from to determine how armor affects fall damage: Quadratic and Logistic.
By default, they correspond to these two graphs; quadratic is blue, logistic is red.
Quadratic consistently increases the damage multiplier as armor weight increases (hence the largest increases result at the highest armor classes, such as netherite).
Logistic, on the other hand, tapers out at a specified "upper bound" (such that the largest increases happen a little closer to the midpoint of the armor classes, such as iron/diamond.)
Tinkering with the different values in the graphs can perhaps give you a better idea of which feels better for you. Note that there's a difference between the raw graph values, and the numbers in the config. You can check out how they're used specifically here.
By default, the pack is set to quadratic for simplicity's sake. Wearing netherite causes about triple the amount of fall damage as normal (watch yourself in the Nether!)--trust me, it's less drastic than it seems on paper.
In addition, there are other generic fall damage multipliers that can be used on mobs, players, and horses. You an also enable a debug mode to tell you your numerical armor "weight", and the resultant damage multiplier. Feel free to adjust as you please!
Optional Compatibility:
Caverns and Chasms (currently in MCA development; subject to change)
Nether Extension (also in MCA development; subject to change)