The blade shape is Warren osbournes reverse tanto. The rift is the contegos little brother in a sense and has the same blade shape, but comes standard with 154cm. Benchmade does an outstanding job with their 154cm tho so don't let that fool you. I have a rift and contego as well as a 581. I personally like the 810 over the rift for its blade length and handle shape. Honestly what ever benchmade you buy, its going to be a great knife. But honestly, I like the Gayle bradley from spyderco the best. Is has m4 as well, but a nice hollow grind making it nice and thin behind the edge for better slicing. Hope any of this helped