From the depths of uselessness: Redi-Edge Redi-lok sharpener

Yikes. I am not a fan of carbide sharpeners in the first place, and I can’t imagine when I would need to use one in an emergency when I happened to have my AR with me.

from TheFirearmBlog:

Well, the question still remains: why? Can you think of any situation where having a knife sharpener attached to your firearm would come in handy? Maybe this could be a useful accessory for a survival firearm? Won’t it be a potential snag hazard that can also cut your clothes and gear like slings and MOLLE webbing? Sound off in the comments section.

Having a sharpener handy is nice when dressing out game, but the only thing I hunt with my AR is coyote. And I still wouldn’t want a carbide.