What kind of tool is this?

[mmellies]

what kind of tool is it?

[oldgoaly]

a slate roof nail puller?   Seen  This Old House use something like that on a slate roof.

[HeelSpur]

Saw a pic and it said it was for cedar shingles.

[Lewill2]

Yep slate ripper, you slide the thin blade up under the slate and catch the nail with one of the hooks. Then pull or pound on the handle offset with a hammer to cut the nail off.

[Billman49]

Called a slate rip in the UK, with copper nails it can be used without a hammer, with the momentum of sliding it under the slates - if sharpened it will cut off the heads of the nails. Most cut in either direction - push and pull. With galvanised steel nails it will require more force as it has to pull the nail out at 90^o to its axis. I see no reason why it should not be used with wooden shingles as well. In France they are called an 'arrache-clou or tire-clou d'ardoisier' and are generally a little shorter and much more aesthetically shaped...

[Frank]

AHA! I ran across one of these in a bin once and thought it was some kind of sword or something used in skinning/butchering.