Don't get too extravagant with this. Description of appearance is one of the most commonly overdone things with OCs. Keep it simple no one will remember a word you say if you describe everything from the shape of his/her nose to the color of his/her toenails. Also, keep this within the realm of the fandom. In a fandom where characters all have naturally colored hair, it would be strange if your character had naturally pink hair.
Do note the weapon depends on the fandom, the age, the time, the place, etc. Your character may also not have weapons, it all depends. If your character does have a weapon, what type of weapon it is depends largely on the fandom. For example, it would be quite bizarre if your Rurouni Kenshin OC used a light saber as a weapon. And it would be a plot-hole
Similar to weapon, the ability of your character depends on the fandom. If the canon characters of the fando