I am confused(and dont like it ha ha). Are the 17,20,25, settings a per-side angle, or a total of the two. Am i saying this right? I ordered a Benchmade Rant DPT with D2 steel. First BM,first D2. From what I read D2 is hard to sharpen. I will probably want to, at the very least, improve the factory edge.I e-mailed BM and they said all of their edges are ground to 15-17 deg. PER SIDE. So, would I use the 17 or 30 deg. slot on the Lansky guide?