Doron was a master dwarven smith, but even masters make mistakes. While disassembling a suit of "worthless elven chain" - for research, of course - he accidentally dropped several links into his forge, and that trace amount of mithral tainted everything he made until he could scour the thing from top to bottom. Each suit made during this time was infused with strange magic, but Doron threw them all on the trash heap, and was known to slap anyone he saw wearing one.