It's about a boy who have a hammer as a weapon, which is very heavy. His father died protecting hiim. The manga is about him having an adventure. He also has some companion. One of them has handsome face but small body and he has to wear a mask to hide that.
It is crocket!. http://myanimelist.net/manga/17005/Croket!
I have found it after scanning 600 titles on myanimelist
Is it MÄR.
I have not read it but he do have some kind of hammer weapon
He seems to have quite a lot friends. But i can't find something about his dad.