Having trouble with some of the items

[CircusMaximusBC]

all the stuff under the 4th tab wtf is that stuff for? i know some of them are spells i get that but the other stuff ? also sometimes under the armor and stuff i will get useable items and when i go to use them they disappear yet i dont notice any stat boosts or anything like that so what are they for exactly?

[Shiroyu]

The fourth tab is reserved for "special" items such as techniques, enemy parts, grinders, materials, and mag cells.

The items that appear underneath your armor are units, which are equipped if you have slotted armor. So in other words, you weren't using them, you were throwing them out. <_<

[CircusMaximusBC]

well **** i figured i might have been throwing them out lol oh well learn as you go i guess , what are enemy parts used for

[Zarode]

Used in the underground store (unlocked after you beat the third chapter on any story mode), you talk to the old man under there, pay a fee, and you get a weapon out of the item you got.

[Aki_Yoruno]

If you want to equip those slot items into your frame, you have to go to the 2nd option in the main menu, which is the equip section. Sorry, can't equip slot items in the regular "item" screen. I know, kinda annoying.