I was adding weapons from other mods and when I loaded up Minecraft the next day, all my edits were changed to

[custom_weaponry.Weapon name here]
registry_name = "broken_item"
weapon_type = "SWORD"
impact = 0.5
armor_ignorance = 0.0
hit_at_once = 1

all of them,
and it would do this while the client was running and straight-up deleted three weapons I had just added
for now I would backup the config file so that it can't overwrite it

After playing for a while it stopped reseting

That's because the configuration reader encountered an invalid value for custom setting. Can you post the configuration file here?

epicfight.toml.txt

I Had to change it to a txt

It works perfectly on my computer. Can you post the log file when the config file breaks?

So.. It's completely solved now?