I don't think personally an edge can be too sharp, but I do think you can hone an edge past its physical capacity to maintain its structure. I'd personally consider an edge that is so fragile that it dulls quickly to be essentially overhoned. I think you may be meaning the same thing and we are just quibbling over definitions, but perhaps I am wrong (it's generally the norm, actually).

I'm never sure when I say this whether it helps or hinders, but I have always thought that the secret to good honing is knowing when to stop. Not that I am saying I can put that into practice all, or any, of the time, but I do know that when I keep that idea in the back of my head my honing comes out better, generally. Yes, it is kind of vague and lacking in detailed instructional qualities, but it works for me.

James.