Currently, there are several types of permanents
1) Weapons, of which you can only have one out at a time
2) Shields, of which you can only have one out at a time
3) Others, of which you can have several out at a time, such as Boneyard
However, the game uses the same icon for these different types of permanents. Most decks only need 1-2 copies of a weapon and 1-2 copies of a shield, but can use up to 6 copies of the other types of permanents. For new players or for when new cards come out, it would be easier to identify what kind of permanent a card is if they have different icons in the lower right corner of the card's picture. That way, we won't have to put it in a deck and test it out to find out where it sits on the gameplay field.