Some of our oldest and most enduring legends handed down incorporate magical, spiritually-oriented themes with literary roots from pre-Christian pre-monotheistic “God”-oriented traditional tales. The legend of King Arthur and his Knights of the Round Table almost certainly took shape in oral form well before Christianity took hold in Medieval Britain, the quest for the “Holy Grail” was grafted into it perhaps by the French monk Mallory when he collected and committed those tales to written form, it provided a bridge to ease and wean ordinary humans from their familiar traditions and into those of later religious Judeo-Christian belief.
Homer’s Odyssey also tells of humans in a polytheistic pre-Christian society which tried to explain its environment in terms of interfering quarreling gods with very human failings. There are very spiritual tales about interactions with humans by fairies and goblins and sea creatures in Western mythology that are beholden in no way to religion, the multiple gods of Greek and ancient Egyptian times, the flying carpets and enchanted lamps and genies of Arabian tales, dragons and cracked bells in Asian myth, all of them relate to intrusions of a conceptual otherworld into the world of humans and vice versa.
Several enchanted sword legends besides King Arthur existed, Cuchulain in Ireland, Roland in Carolinian tales, others) that usually involved non-religious but other-worldly meddling by magical creatures and beings. The “enchanted sword” factor might have come about because their iron swords, which came first, were often brittle and rusted up easily and broke in battle; but occasionally while being forged, a sword, likely by accident before the process was understood, was contaminated with carbon from burnt matter in the furnace and emerged almost supernaturally changed into this beautiful strong steel, with all its superior qualities, and of course such a sword must be given a name and could only belong to one who could be proven worthy of it. How else to explain such magnificent strong blades unless through magic?
Once Christianity and Catholicism began to take hold, spirituality appears to have been stolen away by jealous churches, can’t have your faithful flock turning to other sources of power and magic except through your own deity, now can you?