to keep the convex edge, its not much what you use as is how you use it
i would recomend trying to sharpen convex/ grinding them first, some cheaper knives, to get the hang of it
its not difficult, but its different, and its better to have a good idea before you start sharpening that F1...
a flexible cloth mouse pad with fine sandpaper is a good convex sharpener
or/and a piece of leather, with some abbrasive compound
or you can have more leather strops, with different compunds, from high abbrasive to low/polish...
ussualy a bit of stropping after almost every use, using some compound on a leather strop would suffice to keep it sharp and maintain the edge
watch some videos on you tube with convex sharpening, use google for some info, or the google search in bladeforums :
http://www.google.com/coop/cse?cx=011197018607028182644:qfobr3dlcra
, to get an idea on how its that convex sharpening done
it looks hard, but its not

anyway, lets see some other advices, since im not an expert in convex edges sharpening, as many of the members here are
cheers
