The Spirit of Summer one of the few minipets in the game that is treated as an actual summon. Because of this, you will see the words "You perform Summon Spirit of Summer" within your combat log if you use the item.
Patch 2.4.0 (25-Mar-2008): Changed from common quality to rare.
Done so it can not be easily or accidentally deleted.
Patch 2.4.0 (25-Mar-2008): Changed from quest reward to purchasable item.
Was a reward from the quest  which began and ended with Festival Flamekeepers in each race's capital city.