Why do you complicate?
Weapongrp.dat opened, copied lines, looked at the patch to effects - copied these files, copied the libraries ( because the files are encrypted with smart crypt, which means you need to copy two libraries to work with them ) and everything will work.
Example:
0 8137 3 1 15 5 0 LineageWeapons.doom_crusher_m00_wp LineageWeaponsTex.doom_crusher_t00_wp icon.weapon_doom_crusher_i01 -1 1900 51 1 0 14 2 1 LineageWeapons.doom_crusher_m00_wp 1 LineageWeaponsTex.doom_crusher_t00_wp 4 ItemSound.hammer_3 ItemSound.sword_mid_9 ItemSound.sword_big_7 ItemSound.spear_6 ItemSound.itemdrop_spear ItemSound.itemequip_spear 20 282 114 2 4 4 4 0 0 0 325 0 1 1 1000 0 -1 0 LineageEffect.c_u005 -7.500000 0.000000 0.000000 0.900000 0.900000 LineageWeapons.rangesample 1.300000 1.300000 1.300000 18.000000 0.000000 0.000000 5 -1 -1 -1 icon.weapon_doom_crusher_i01
Color = Patch to models ( in your case don't need to copy default models ).
Color = Patch to textures ( in your case EuroWP ).
Color = Patch to emitters ( from .u and etc )( in your case LineageAmonEffect )
So, copy all these files, next textures / staticmeshes from .u can be located in different files ( not in one ) and need to search, it can be ~the same name as .u name.
If you search by key "Amon" you will find files: AmonMesh.usx and AmonTextures.utx, copy these files too.
But be careful, files are encrypted and you may have problems, better to use something else ( another weapon pack for example, now we have very much free styles for weapons and you can choose any ).