Well I'm not a programmer or coder or anything like that. I'm just someone who's always wanting to learn new things ( for example, if anyone's familiar with the GarrysMod Wiremod, they've got E2 chips which basically let's you code cool stuff in the game, I learned to code my own stuff in there with 0% knowledge of coding, just through research and trial and error ). Now I've got a question before I try fiddle around with stuff. 1 ) If I would ... let's say pick an existing sword and only modify it's stats and special attack ( I really like the looks of that sword that throws out an electric star-shaped thingy ) but it's stats are just horrible. Now if I would modify that sword's stats, or modify any of the craftable swords to have that special attack and better stats, would people on a server be able to see and use it, or would it be like a new added in mod that only I myself can see ? ( example : UFO mech mod makes my character invisible to everyone on the server when I got the mod installed ( not even using the mech itself ! ) ). All I wanted to know before I mess around with stuff. I'd like to figure things out on my own, but I'm clever enough to always keep a backup of the original files just incase.
There are two types of "modding" - messing with the assets (editing images and configuration files for the various objects) and API/logic integration. Sounds like you're interested in the first. What you want to do is definitely possible. There are a ton of tutorials on this forum telling you how to go about modifying assets. If you just want to mess around, you can edit the files in there and restore your backup later. If you want to distribute your mod, you probably want to package it up into an external directory and ensure you don't modify any of the vanilla files. Unfortunately mods are completely client side currently. This means any changes you make locally aren't seen on the server or by other clients. Sorry!