So I have a theory about what Simo's weapon may be able to do, but it's only a theory-
A MANGA THEORY
-So Radgridr translates roughly to "Truce of Counsel", so what if her power allows equality between players. We all know Loki is a Trickster God, and would most likely tilt the playing field to his advantage. Would it not be advantageous for their to be fairness in this fight? Make things a level playing field? It would surely throw Loki off his game if the fight was not in his favor.
And this is not to say Simo couldn't defeat Loki with the odds stacked against him, we all know how badass he was during the war. But I would love to see Loki on the back foot after trying to pull a trick and it not even going off because Radgridr already neutralized it.