What Is It? game 214

Once again, it's time for our collaboration with the always amusing What Is It? Blog! Do you know what the object in this picture is?

Place your guess in the comment section below. One guess per comment, please, though you can enter as many as you'd like. Post no URLs or weblinks, as doing so will forfeit your entry. Two winners: the first correct guess and the funniest (albeit ultimately wrong) guess will each win a T-shirt from the NeatoShop.

Please write your T-shirt selection alongside your guess. If you don't include a selection, you forfeit the prize, okay? May we suggest the Science T-Shirt, Funny T-Shirt and Artist-Designed T-Shirts?

Check for more clues at the What Is It? Blog. Good luck!

Update: this scary-looking tool is a slater's axe. It's also called a sax, saxe, slate cleaver, slate cutters' trimmer, slate trimmer, and zax. It was used to trim and punch holes in roofing slate. Anker was the first with the right answer, and so wins a t-shirt from the NeatoShop! The prize for the funniest answer goes to marcintosh, who said, "It’s a Panel Trowel. It’s used for spreading white grout in the gaps between comic book panels. That’s why it’s shaped like a word balloon." That one deserves  t-shirt, too! Thanks to everyone who played along. See the answers to all this week's mystery items now at the What Is It? blog.