MikeH

Correction: He didn't need to see it. He's been next to Miggs for a while, so knows the types of things he does. He may have done this same thing to other visitors.

Corrected entry: When Hannibal handcuffs a cop's hand to the bars, he only handcuffs one hand. He could've used the other hand to shoot, tase or mace Hannibal or unlock himself with his keys.

MikeH

Correction: The guard didn't have them on him. Before he enters the cell we see him pass them to his colleague who remains outside of the cell.