I've been splitting a fair amount of wood recently and all the wedges I've got, both new and old, struggle to initially bite into the log. Their secondary bevels (the last 5-10mm of the edge) seem to be a rather steep 45°. Now I know you want the main part of the wedge to be thick, to force the parts of the log apart, but a sharper edge would bite more easily and make the initial starting off much easier. Is there any reason why splitting wedges don't have a better edge, i.e. is there any reason for me not to sharpen them with a file?