For my personal choice... Maybe the God Arcs from God Eater? It's like Ruby's Sniper Scythe, but sentient and customizable. Just don't let it bite you.
At a distant second, I guess blood drinking swords like the ones from Blood+ or from Seraph of the End.
They aren't as cool-mundane as something like a scythe or lightsaber, but the concept is interesting. Oh, and I guess the Sentient demon blades that are used by the humans in Seraph of the End are also somewhat interesting.
Spoilers for Library of Ruina
Reminds me of the Armiger from Final Fantasy
gun-shaped CADs from "The Irregular at Magic High School" because that's something that can be used by the average (magical) Joe!
In all honesty, I find phone type CADs to be much cooler. You can do all your phone stuff, and then bring down magical hell, all while playing with snapchat filters.