I got an item today that has +2 intellect/intelligence. (don't remember which it is called).
I looked through the in-game guide and there is no explaination for it or it's symbol (yellow circle inside of a yellow square). How does it benefit your character? It doesn't seem to directly effect your mana pool, so how is it beneficial?
This item has confused people before. There is no stat called intellect; "Intellect" is just part of the name of the item. If I remember correctly, this is a ring that gives you an increased chance of getting power (yellow) pips during battle. Look at your character screen and note your power pip chance (make sure to take off any other ring first). Then put on the new item and look again - you should see a higher chance of getting a power pip. The icon for power pip is a glowing yellow circle - see if that appears on the item description right after the + percentage.
About the game -> Player's guide -> Clothing and equipment.
It will tell you everything you need to know. It took a fair bit of searching to find this myself, and I only happened to find it because I was trying to figure out what fizzles were...
I feel that fizzles and the different types of gear stats could be better explained in-game. There's EXCELLENT tutorials on card types in game, but they leave you out in the cold in terms of gear bonuses and fizzles in the game and it takes alot of searching on the web site to find out for yourself.