One of my PCs, a Wizard, found an item of demonic origins. Basically, the carrier develops a sort of connection with a dark entity that affects his personality over time and possibly provides demonic powers.
Another PC cast Detect Magic on the Wizard. I was not sure whether the demonic item would be detected. More generally, I am not sure whether certain creatures/items (dragons, demons, devils, celestials and so on) would be considered as magical in a standard D&D setting.
So, here is the question: can supernatural phenomena (creatures / powers provided by items) always be related to magic?