Oh! I forgot about "MacPherson." Whoops. This is why I need to get season one on DVD.
And I agree about the grappling hook. It probably became an artifact when H. G. invented it, which is why it has a case and place inThe Warehouse,and it's not exactly a common place item (like a cell phone), so I think it should stay listed as an artifact. Plus, like you said, the way it was used just makes it seem like there's more than meets the eye.
As for the grappling hook - I state it again, artifacts are not artifacts simply because they aren't commonplace (like a cell phone); the warehouse staff themselves use gadgets like the Tesla gun and the video phones that aren't commonplace, but those aren't artifacts, either. It's an artifact if it has a power that goes beyond human understanding (and thus may be potentially dangerous), i.e., there's a supernatural element to it. The grappling gun is just a gadget. Might be one-of-a-kind, but it's still just a gadget. Otherwise, everything that's ever been invented would go straight into the warehouse, and we'd be still living in caves.