"Shall" is a little more flowery because it's not used in common speech anymore (at least in the States; it may still be somewhat common in Britain). To an American ear, it sounds poetic or purposefully ironic in an attempt to sound poetic.

Thank you very match. Sometime it is so difficult.

''You shall meet me!!!'' - like a warning or threatening? Three witches you shall meet,on the path to your fate. One will deceive you, one will relieve you, and one will show you the way.

"Shall" is preferred in British English; "will" in American. "Shall" is still used in the states, albeit in more formal contexts, whereas "will" is always informal. If an American uses "shall," he or she could be speaking more demonstratively or being somewhat pretentious.