Yes, I agree NJO Luke<Exar Kun<DN Luke..However...
The amulet blasts were NOT continuous blasts, Kun only used it once before he was scared to death of it. It nearly killed him. The AT-AT blasts tear through everything just as well as Kun's blasts, there's no way to put one ahead of another.
Nevermind I see what you mean by continuous now.. And either way, it's hard to say which one is better and I didn't say Luke COULD necessarily block the blasts, but it is a possibility since we've seen him block something as powerful as an AT-AT blast.