"Runes are only used in the cities by the high archangels. It is forbidden to use them in any form or else it could be a sign of war." Elane made this very firm. It was proof that there were many things that had happened but the use of runes being banned? That was a ridiculous.
"Let me take a guess, Runes were used in ways that caused many angels to die between both empires?" Walker never intended for runes to be used for wars, but he understood that they could be. It was too easy to see that potential.
Runes were able to gather elemental mana without the constant care of someone else. If they were made in the right way, then they would be able to influence massive amounts of elemental manas to cause catastrophic damages.