Someone or something that puts shackles on people or things.
The word shackler can make people think of being trapped or controlled.
Examples:
The shackler put chains on the prisoner.
The evil wizard was a shackler of souls.
The shackler locked the door with a big lock.
The shackler tried to put chains on the cat, but the cat ran away.
The shackler put chains on everything in the room, even the chairs and the table!
The shackler's chains were very strong and heavy.