Ranger magical items

How do use use items that give you +energy and such. I noticed for a while I had a symbol on the upper left giving me +energy. I don't have a clue how I did it. What items are specific to a Ranger? The guy next to Nente gave me a Grim Cresta, a sort of a glove. But how to use it???? I know part of the game is learning this stuff, but sometimes I want the option of just knowing ?

To use these foci items, you need to use a one handed weapon, which a bow is not. You hold them in your offhand like you would a shield.