What did Makee take out of her finger?

What did Makee take out of her finger? Makee feels a great connection to Chief after this that she seemingly decides to abandon her ties to the Covenant. To do so, she removes the small laser knife-style weapon that was previously in her index finger.

Makee feels a great connection to Chief after this that she seemingly decides to abandon her ties to the Covenant. To do so, she removes the small laser knife-style weapon that was previously in her index finger.