If you went back to medieval times and wanted to impress a knight, you might compliment him on his shiny pallettes. A pallette is a metal plate on a suit of armor.
When you spell pallette with two l's and two t's, you're talking about an armor plate, specifically the rounded pieces under the arms. The word pallette is rarely used, and when it is it's often a mistake, since it can be tricky to distinguish pallette from palette, an artist's set of colors, and pallet, a kind of makeshift bed.
