In my opinion, Shadowmere is the best horse in Oblivion because while the other horses panic, he fights by your side.
When I began to mod a doll so that I would have my Dunmer character, I decided to make Shadowmere for her.
I took a pink plastic horse (a Barbie knockoff) I had bought at Goodwill for a dollar or two and ripped out its tail, cut off its mane (I had ripped out its mane and tail months ago), spray painted it black. After the spray paint dried, I painted his eyes red with acrylic paint then used a gloss sealant on them so that his eyes would have a shine to them like real eyes. After his eyes dried, I gave him a new mane and tail using my own method.
And now my Dunmer ,who is not yet finished, can ride the noble Shadowmere.
From the front:
From the side: