All.blend - It's not lib, contains all meshes from Bows.blend, Claymores.blend, Polearms.blend, Swords.blend
GenshinImpackWeaponsAsset.zip - Asset lib for Blender 3.0.
The rest match the name.
How to setup Asset Browser
1) Donwload GenshinImpackWeaponsAsset.zip and unpack to folder with name GenshinImpackWeaponsAsset.
2) Open Blender go to Preferences > File Paths > Asset Libraries.
3) Go to the folder where you unpacked GenshinImpackWeaponsAsset.zip. For convenience, I created a folder "C:\Users\UserName\Documents\Blender\ExternalAssets\".
4) Give a name for the asset, I gave the name "Genshin Weapons" but you can name it whatever you like.
5) Go to Viewport add Asset Browser.
6) Select Genshin Weapons.