Discretionary Title??

Episode 4. Victoria has within "her gift" the ability to make the wife of her uncle Duchess of Inverness.

I thought a discretionary title did not come with a peerage, as in "Princess Royal," the title given to the Monarch's eldest daughter, who in not a peer (current holder, Princess Anne).

But Cecilia was made a peer in her own right. The peerage became extinct on her death as she had no male issue.

I don't know why this is called in the show a discretionary title. It was a peerage. The Monarch has the power to make anybody a peer (though these days, by custom, no non-royal is created a hereditary peer, and life peers are created with the advice of the Prime Minister).