That's a client problem. All sprites are inside the .grf files in your ragnarok folder. If you have the sprite prepared, then you need to
go in the item_db and find your item, it will have a part of it which says:
AegisName: "Valkyrie_Helm"
Name: "Valkyrie Helm"
Type: 5
Buy: 100000
Weight: 1000
Slots: 4
Upper: 58
Loc: 256
View: 225
associate the view number with the number of your sprite. I don't know how to assign a sprite a view number, however. You can probably find that in a tutorial if you google "custom headgear hercules".
I've never even seen that item, so if you're asking for us to give you the sprite for it you're in the wrong place.