I have just managed to de feather and hog my daughter's coloured HW cob with our Liveryman Harmony battery clippers. They don't whizz it off like mains heavy duty clippers but have done the job, taken a bit longer but decent result.
Wouldn` t it look like you had clipped it off when the top of the leg is so hairy and the bottom is then clipped? I thought that trimmers would grade it in better?
I've taken long hairs off back of legs above knee and graded it ok. It is harder to get 'the seamless look' in winter but after a few days it does look much better. TBH the Harmony clippers aren't heavy duty so I use them for blanket clipping and trimming so only one pair needed and they are nice and quiet for doing moustaches and ears too!
I've used harmony clippers on feathers and they don't get very far atall, I now use lister liberty with coarse blades to get it all off, then the harmony ones to get rid of the lines and grade it in
I use a set of Masterclip trimmers on my boys thick feathers.
He won't let you near his legs with the big clippers even after several doses of sedative but will stand happily for hours while I clip with the little trimmers.
It does take a lot longer so I try to keep on top of it as often as I can. If I do leave it longer than I should have then I hack most of the hair of with scissors and then tidy with the trimmers.