Looks like a typical mid 19th century hollow handle butter knife to me, American coin silver with pseudo-marks, most likely from New York state. My guess would be a 'W', but an 'M' is also a definite possibility - somewhere in the back of my head, seem to recall a similar mark connected to Albert Coles successor Morgan Morgans, Jr...
~Cheryl
Similar Albert Coles mark as well as one with an anchor, both found on butter knives:
![Image](https://www.925-1000.com/pics/Ximg.jpg)