User blog comment:Gundam Legilis/Volume 2 Intro In Depth- Velvet's Team/@comment-4834824-20140528004455/@comment-6975131-20140528130719

I'm sure the grimm we see are as basic as it gets. And the narroraton said that the Grimm were a threat before all these fancy weapons were invented, even the most basic models of weapons using dust were enough to fight them off, so it really is no suprise that at this point, they aren't a very lage threat.