Valkrionn
The Hamster King
First, I'd like to say this is an excellent idea... I'm willing to help with whatever you need. Of course, that's partially so I can later steal it...
The main issue here is that it took direct intervention by Kilmorph to imbue Mithril with the necessary magic... Although you could get around that by saying it's just an Iron Golem, in Mithril armor.
Explain? They clearly have some interaction with Mythril, given one of the Golems is only available AFTER Mythril Weapons tech. What's so terrible about Mythril Golems as an analogue for others having Mythril Weapons? I assume you're considering the Mythril Golem hero, but, well... he's a Hero. If all else fails, we rename him Mythril Titan to differentiate him.
The main issue here is that it took direct intervention by Kilmorph to imbue Mithril with the necessary magic... Although you could get around that by saying it's just an Iron Golem, in Mithril armor.