Three yes, but it is according to her so slightly biased, but more so top 3 isn't #1. Plus that is only in regards to people who use blades. Though that does make him stronger than most champions (due to blades being so common). Swains martial prowess is hard to judge as many of his fights that have been shown are hinted at being tricks. Such as him fighting J4 or the old leader. However it does say that he is usually at the front of battle, and yet he is still alive.
He has been shown to have a high strength of will though:
"According to them, Swain limped into the ward without cry or complaint: his right leg was snapped in half, with bone protruding from the skin. A small, scowling bird seemed affixed to his shoulder. The doctor gawked in horror as the young adolescent answered questions about his health and age with a calm, even stare. Even behind the echoing crack as the sand counterweights reset his tibia, Swain’s measuring gaze never flickered, nor did his eyes twitch from the pop of his fibula. He refused the doctor’s recommendation of magical treatment for the leg’s inoperable damage, requesting only a spare crutch before shuffling away. "
And it wasn't a question of who is the best fighter, but best over all. So intelligence is a large part.