It will still cut without thinning the edge. It did want the edge cleaned up, though. It felt kind of jagged to me, as if they stopped after the coarse abrasive level and skipped the fine grit step. AUS10 does not require diamond stones. It does want at least an aluminum oxide stone, though. It has chromium carbides, which are harder than natural stones. A Norton India Stone would work.
Blade length is a judgment call. I tend to prefer a 3" blade. For me 3" is the right size for the tasks I perform with a knife on a daily basis. Opening boxes and clamshell packaging. Trimming flash off of plastic. Small cutting chores. A larger blade feels unhandy to me, which is unfortunate, because I love large blades for their beauty.
As for the handle length, I have medium sized hands and wear medium sized gloves. I get a full grip on the handle with all four fingers, which was something I was looking for. I have several nice 3" bladed knives that I seldom carry because the handles leave a finger hanging. But if you have large hands, you may need to look at something else if you want a full four finger grip.
Edited to add:
One additional thing I did. I used a razor knife to cut striations that run lengthwise along the edge of the handle. This gives me a better grip when opening the blade. The thermoplastic handle is plenty strong and has steel liners to boot. And the flat surfaces are grippy enough. But the edges are smooth and I found a tendency for my hands to slip a bit when opening the blade if they were slippery. The striations fixed that.