How does the Orb of Wisdom give its trait?

The description says "Unlock the next trait". Does that mean it will unlock the next trait, going from left to right, or does it give you the option to pick which trait to unlock?

Solution 1:

See: Gems of War Fandom Wikia

Minor Orb of Wisdom will give the troop its next trait. For example, a troop with no traits will get its first trait, and a troop with two traits will get its third trait.

Major Orb of Wisdom will give the troop all remaining traits. For example, a troop with no traits will get all three. A troop with two traits will get its third trait.

So, to answer your question: The traits are unlocked from left to right.