When a magical item became a Legendary Item and then became a major Artifact, gains
it gains the suite of base legendary abilities and can have up to three additional legendary abilities. By selecting the legendary item universal path ability more than once, a mythic creature can transform a normal legendary item into either a minor artifact (if the character chooses it a second time) or a major artifact (if the character chooses it a third time). A minor artifact legendary item can have up to six additional legendary abilities, and gains the difficult to destroy ability (see below). A major artifact legendary item can have up to 10 additional legendary abilities and gains the difficult to destroy ability.
Now a wielder can use hits
Legendary Power: All legendary items contain a pool of power—at least two uses that recharge each day. This power is called legendary power, and it works differently than mythic power. Any creature bearing the item can expend the items uses of legendary power, whether or not that creature is mythic. These uses of legendary power can be expended only to activate the legendary item’s abilities. If the item’s bearer isn’t bonded to the item, she can expend the item’s legendary power only to use its legendary surge ability.
For example the wearer can use the Legendary Surge of the legendary item two times during a battle and then stop.
The question is: Now a wielder can use almost 13 (10 + base) legendary powers from the item but only for two times a day, "a pool of power—at least two uses ". Who decide the number of uses?