I really love this. With it's great design and substantial weight (this is just a terrific object to hold in your hand), it feels lot like a Carl Auböck piece--and he did a number of letter openers, including I believe a ruled one--but there is no mark anywhere on this that I can find. Clearly, it is intended as a letter opener, and looks just great sitting on the desk, with a handy six inch ruler on the back. I do wonder if it was designed as a tool to be used for anything else...drawing a curve? Turning something? I'm not sure, but I do think it would do the trick as a bottle opener! 

8 1/4" long x 3" wide x 1/4" thick, this piece is in very good condition, with a nice warm patina to the brass, which I have not touched. There are some light scratches and some aging to the brass, with a bit of spotting/very light pitting on the ruled side. I do believe it would polish up some if desired.