Probably more than you wanted when you asked, but here goes … I guess I would put cutting bread down to using the proper knife, and the technique of using it. Like any tool, a bread knife works great on pretty much any bread, when used properly.
As evnpar/Richard already mentioned, a serrated knife is a must. I think of a serrated knife as a saw. Like any other saw, only the tips of the serration on the blade do the cutting. The rest of the blade, all of that pretty, curved, area between the tips, is just there to support the tips doing the cutting.
A second “must have” for me is an offset handle. I do not know why there are bread knives without offset handles. I used to use a $5 NSF, white handle, bread knife from the restaurant supply store. I splurged, I upgraded to a $7 NSF, white offset handle, bread knife from the restaurant supply store. The offset handle is worth the extra $2.
When cutting bread, any bread, any shape, hard crust or soft, I use my serrated knife/saw, and I ‘saw’ back-and-forth, without pressing down. Once the blade makes purchase, I begin gently pressing down as I saw … the sawing, back-and-forth, always has priority, not the pressing down. A good starting place is anywhere the bread was slashed before going into the oven. The uneven surface makes getting a purchase quick and easy. If I am cutting a small piece off a smooth, hard crust (like with a boule), I hold the blade at an angle so it is perpendicular to the crust. A couple quick, short back-and-forths will make a small groove. Than upright the blade in the groove and make a clean, vertical cut. After doing it a couple times, it becomes second nature. I don’t even think about it, and it is very quick, clean cuts.
About sharpening a bread knife, actually, any serrated knife … you only need to sharpen the tips of the serration, not the whole blade. It’s kind of like a chainsaw – the whole chain does not get sharpened, only the teeth on the chain that do the cutting need to be sharpened.
Here is the $7 knife I use (bought locally). You can get it for $16 from Amazon. (You didn’t really think Amazon Prime shipping was ‘free’, did you?)
I will take that $7 knife over this $160 (MSRP $200) bread knife because it does not have an offset handle.
If I ever have to replace my $7 bread knife, I’m going to get this one for $6.31 and save me some serious money so I can go on vacation!