Shazam In Shining Armor

Rocket Comics was an anthology printed by Maple Leaf Publishing in Canada during the 1940s that had its own Captain Marvel rip off. Little Bill(having nothing to do with the Bill Cosby prequal)was a lad that was rescued from being marooned on an island by a passing ship. His save is short lived as the lighthouse they were following in a storm goes out and their boat crashes into the cove. The lighthouse is run by the evil Grundy who smuggled military contraband and dowsed their light to loot the ship's cargo. Bill and his friends are imprisoned by the crooks, so he says the magic word Umbra which transforms him into an armored adult known as the Black Knight. This super-strong Round Table reject turns on his opponents but manages to spend a considerable amount of time out of frame. The title character is regularly seen outside the comic panels like he was the mysterious villain from a murder mystery,. How Little Bill gained this power doesn't seem to come up. The idea of a kid who changes into an older superhero was pretty common at the time, but so much of this is left unclear as to Bill's origin and what his capabilities are. He's pretty much just a hero haphazardly dropped into someone else's crime story. There is having a shadowy backstory, where Black Knight's is a whole other level of obscurity.