Such large steel tool need not weigh much...I guess that glaive was about five pounds.
The gaive from that Bible was reproduced by a friend not long ago
http://www.youtube.com/watch?v=8JevwURrwQA
Michael is a good smith and so were those in Medieval Europe. By putting just enough metal in just the right places I think you would be amazed ay how large you can go and still be useful.
Ric