I've been having trouble with two things: 1) Is there a way to make/find mud easier? 2)How do you put charms on weapons since the instructions I'd read were unclear about it.

Fujiwara Takuya
Mud is found in swampy areas which appear on the map with purple marks.
Only weapons that require you to make an intermediate part can have mods. You'll see a circle next to the material showing it can accept a mod. Take the mod (in your case, the charm) and drop it atop the material. It will be placed in the material. Then just craft the weapon and it'll have the mod in it.

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