Look up Soluna Blade in Mabibase.com
https://mabibase.com/item/41233Open Itemdb.xml
Ctrl + F (find) for the item ID from soluna 41233
Look for the File_MaleMesh or giant varient File_GiantMesh
File_MaleMesh="weapon_c4_sunmoon_twohandsword"
Reference mabibase.com again for when the file was introduced into the game for what .pack you should be looking into find the PMG file.
"Introduced in revision 229"
From there use an unpacking tool and just search for the Mesh name above for either the human or giant version and you'll find the PMG you want.
you might need to use the normalizing PMG converter too to change it form v3 to v2 so its compatible with PMG viewers/editors.