It has been explained to me, though I am sure I don't remember every detail is that any armor or weapon that has been improved to better than normal standards is considered magical. I think the reasoning in this comes for monsters that have to be hit by magical weapons, better quality than conventional, and that involves stuff that is +1 or higher. It was discussed in a former post. I wish I knew why some glowed and some don't. It may be that the ones that glow can cast spells or have special defenses, aside from dishing out major damage. I hope that someone else can help me with this, especially if I am wrong.
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Larry, Sell-Sword to the OHF