I'm assuming you mean the items in the top right of paperdolls. Those are talismans, most have properties that aid with certain monsters or crafting abilities.

Some basics:

The boosts to crafting only effect your % chance to create an item, not enhancing. This would be good for gaining because you can create more items at a harder level to get better gains.

Boosts to fighting monsters are either 100% to certain types (slayers) and effect damage output, depending on what is says it could effect either damage output or damage taken for specific monsters.

Also talismans have special abilities, an example:

Talisman of Clean Bandage Summoning - this will give you 10 bandages in your backpack when double clicked.

You can read more about them here: http://www.uostuff.com/index.php?title=Talisman