I think those two weapons are different in many regards. They are different in many regards.

Mjolnir was a weapon of the Gods. Forged by the dwarves who were master-craftsmen. It was a weapon of legends. But, it didn't stop there. At our groves Thor was a popular god. He was both a master of the masculine fertility as well as a master of war. That was a good combination that appealed to many of those who lived along the Northern Path. Thor was by far the most popular God to sacrifice to. The irony is that he was not the most powerful. That would be the King of Kings, The Father of All. But, peasants knew that the power he gave had it's price. And those who walked in Odin's footsteps would be at his mercy when they died. They risked to wander the earth as undead for all eternity. That was a high price to pay. So, Thor was a safe God to worship. He was an aspect that took care of the things that worried people the most, weather and bravery. To this day, the warrior-aspect of the God Thor is still remembered. There are groves where the hammers stood. You could feel Thor's presence at the groves once blood was given to him. You could also contact the Volves which were women trained in the dark arts. They had access to the spirit-world. So, the hammer is a totem. A place where gods reside. The talisman of Odin is still worn around many necks as a token of respect to the old Gods. I must tell that when I am at the grove nearby I can feel eyes watching me, and see the ravens circle. It has been hundreds of years since we fed the Gods, but the ravens of course remember. They are thirsty and want the old Gods to live again. This is how the hammer is still alive in our culture. Recently, metal musicians have started to use the hammer as their symbol. And they go to great lengths to learn the old ways. But, we all know that Mjolnir belongs to the realm of Gods. The symbols we wear are only symbols.

The story of Arthur is about a king of Britain that has a fate connected to the land of Avalon and his country. The physical Avalon was destroyed over a millennium ago during the massacre by the Roman empire. But, it is foretold that in the final battle of Britain Arthur will return from Avalon to fight once more for the country. Then the sword will of course resurface and a hero will wield it. Avalon is today a spiritual place, and you will find only dead people at the island of Angsley in Wales. You will also find Christians that treats this place as their own. Excalibur is a physical weapon that will be wielded in a coming war. It can be that we find the actual sword at Angsley and that leads Britain to a new victory for their very existence in the future. It can also be that the sword has to be reforged. But, nobody wears the Excalibur as a talisman. It is not a talisman or a symbol. It is a weapon for heroes in a time of great distress.