Mounting blocks. This isn't a livery stable, but if it were, there would be a rack for barding and possibly a hoist to lift the armored knight onto his mount.
Glad I could help. If you want it, here's a quick-and-dirty hook object. This image is released to the public domain. It's not perfect—for one thing, the profiles of the bend and the end are different. You could possibly make one that is mounted slightly crooked, to make it more obvious what it is, although at the tiny scale you'll be using, it may not make much of a difference.