Is there a better website that explain items?

There are a lot of items in this game that don't specify what it's used for (other than crafting) and if it's important to keep or sell. When using this website & a few others on google, the item description only provides minimal of the item. Most of my things are just filling out my inventory (including my retainer)

Is there a better website that tells me what each item exactly do (in-depth), where I can find a specific item, what are the % rate if I need to kill an enemy, how to use an item & such?

GamerEscape isn't too bad. It'll at least tell you what an item is used for. https://ffxiv.gamerescape.com/wiki/Main_Page