Piccolo made Gohan's sword. Master swordsmith and clothing manufacturer. He could have made it sharp to protect Gohan, since he knows Gohan isn't that strong usually. Or not sharp so Gohan will use his power more to cut.
But this sword has to be able to withstand Gohan's full power. If Gohan misses an hits the ground with his sword with huge amounts of force, it needs to withstand that without breaking. So probably his sword was made stronger.