There are actually two definitions of the word "katona."1,a soldier,2,a sandwich cut up to bitesize.
Why reggelt? Because it is an object?
The original phrase is "Jó reggelt kívánok!" = "I wish (you) a good morning."
Why is it sometimes "reggel" and sometimes "reggelt"?
Reggel is nominative and reggelt is accusative.
See the comment above yours for why its reggelt here.