This is just a plain book of melding used to put covers on without any + on this book of melding in LastChaos. If you had a 15 weapon and you just want to put a cover on just for looks. The Knights dual covers which look like fish bones, whereas the single sword cover is just a plain bat look. Same rules apply as far as not trading, selling, and you need book of unmeld to take cover off, if the time has not expired yet. Effects last 30 days.
Covers, Uniforms, Gang Outfits which is in the item (lastchaos money) mall are numerous covers to aid you in upgrading or if you just want something different from the usual armor. The items that say level 3 or level 17 is the level for that armor now. So Buying level 3 Japanese armor is not worth it as when you get to level 10 you would want armor with more protection. Also, new western outfits and Samba outfits are available in that they have head cover that you can meld. The other outfits do not have head cover to meld.
That you must note that chaos smelting stones are expensive and hard to come by. You would better to save them for the level (cheap lastchaos gold) 85 weapon and armor set. You can always shop around and start pricing armor and weapons in the Level 85 level. Depending on money and stuff, you can hopefully get enough hs, lss, and css. Use hs to get from +1 to +3, Lss to get to +6, then Css to get to +12. Now the option is to use an ES to get to +13 an then use +2 bonus book with cover to get +15. This will last 30 days.