Not to mention the Acme bottle for making mix-and-match mercenaries...
From the comments on NC's site, that one did get an explanation. The villain mentions he got it from witches, and the NC either didn't think that was enough explanation, or missed it. Same with the healing leaf. The characters mentioned that the leaves have healing properties, and the NC missed it.
But in Camelot lore, there wasn't "rampant" magic. It was carefully harnessed by wizards. An enchanted wood would require an explanation of "Haunted" or "The witches cast a spell on it" etc.
The complaint should be that this doesn't match up with Camelot lore, not that it needs explanation. Why spend time on an explanation of how an enchanted wood became enchanted? It is how it is. What if the explanation was "A wizard did it." How is that any more satisfying than just accepting it as magical?
With magic explanation is needed when something
isn't possible. Why
can't they just melt the ring in a forge? Why
can't the good faeries just undo the evil curse? No one asks how the faeries got their power in the first place. There's no point, unless it advances a character or the world. It's not about how, it's about who.