The Shining Knight’s series ends with Adventure 166 (July 1951), and it goes out on a decent note. Frazetta may be gone, but this story and one in the previous issue were drawn by Ramona Fradon, and the art is more than passable.
Sir Butch accompanies the Knight to Mexico, where they come across a lost Aztec civilization, and bad guys who want to enslave them. The Aztecs are lead by Quetza, who turns out to be their princess, who dons men’s armour to face down invaders.
At some point after this story, the Shining Knight joins the other Seven Soldiers of Victory in their battle with the Nebula Man, which displaces them all in time. A double displacement for Sir Justin, I suppose. He next appears in JLA 100 as the Justice League and Justice Society track them all down.
Sir Butch has never appeared since this story. As it ends with Quetza inviting Sir Butch and the Knight back, I take it that Butch and Quetza hit it off, and he wound up marrying her and living with the lost Aztecs for the remainder of his life.