A Targaryen names Baelon born mutated with left arm, right leg and some parts of his face and back covered in scales . On his left hand are only three fingers and thumb tipped in claws same with the right foot which has four toes tipped in claws alongside a tail covered in scales that can be used to knock back enemies, his teeth are sharp like a dragons his physique is broad and muscular and is 8 to 9 ft tall with freakish strength (picture the mountain for the build but not looks) long silver hair that's braided (picture khal drogos hair) favoured weapons are polearms mainly halberds with acceptable skill with the sword. Eyes are either amber in one and lilac/purple in the other or both are just Lilac/purple. Quick to anger but not controlled by it prefers things to be simple and straightforward instead of complicated schemes, takes great pride in his Valyrian heritage and enjoys reading Valyrian and the ancient untold history of westoros both the good and bad sides (pretty much picturing the book untold history of westoros).
His dragon would pretty much look like ghidorah with the three heads. Has fire breath that's golden in colour and be able to heal from any wound as long as one of her brains are intact enjoys flying in storms will grow faster then other dragons and be extremely temperamental only allowing his rider near him and will eat any one that comes near him unless they're accompanied by her rider also enjoys eating dragon eggs. Due to having three brains she is smarter than other dragons.
Valyrian steel would actually be superior to other steel weapons and be able to slice through them only exceptions would be weapons like dawn that were made from meteorite aswell as magically enhanced weapons like lightbringer thats been temporarily blessed by the lord of light and the javelins the night king uses.