Those are some very good points
Yes I'm sure that in living in caves all his life he probably is a very clumsy flayer and probably wouldn't get any better if he didn't leave(though he may never be a strong flyer cause he's been grounded for too long and nether one of his parents strongly excelled in flying). Given that he can fly and surely his mother and father,
as flutters, would have taught him
somethings he still wouldn't be nearly as graceful as his parents, dwelling more on living on the ground then that of in the air like normal flutters. Surely thinking flight would only put him in danger.
So I'm going to go with the fire resistance. Naturally his body is immune to the burns of the fire he creates. But since he's such a week flyer (and even if he trained with flutters in flight he may never excel in the skill. get better, but never excel in it.) Surely he's had to hone in on his special skill of fire and protecting himself, rather then in flight and fleeing that the flight options. So, yes, I would assume that he would indeed be resistant to most common fire that isn't enchanted.
Concerning the fire sword:
I've thought deeply on it and given his situation he may just do well with actually possessing a sword. Not only would it give him more training where magic could only get so strong without a real opponent, he could continue his training as a swords-pony. Especially since he cannot fly strongly and considering his father could have, upon his death, given a sword to his only son that could burst into flames. I think that would work if its ok with you that is.
So in the end I'll give up being a strong flyer for fire resistance.
Powers.
Utter flutter: The only power of flight he knows;
If holding still in flight, he can create a powerful wind that push's an "enchanted" air at his opponent pushing them away.
Note: He is not aware its enchanted. He's never met anything like the smooze and would have no idea that his wind powers have a natural magic to them. He would have to have someone
tell him that.
This is his less worked and weakest power compared to the others based on the lone training of 19-20 years would make it if he trained regularly on his flight. Though its a strong utter flutter compared to other flutters because he
has trained in it with and (some) without his parents. But given his current location and training he can only use it when holding perfectly still in the air, because he seldom uses it in training, only under special circumstances. This power is less effective then the others he uses.
(ok I put a condition on this. Because he's not a good flyer, the only power he uses is a strong one compared to other flutters. But he can only do it if he holds Perfectly still like he would in the caves. This at least makes it a strong attack but leaves him vulnerable where a normal, well skilled flyer would simply move if attacked during.)
Flame sword: A sword given to him by his father that possesses an enchantment that, when lit, alights the sword surrounding it in flames.
(thats how the sword would work if it was a physical thing then a power. But I'm not sure if this would be a power cause he could bring the sword up to his main and set the thing aflame. I dunno. )
Fire circle:Fire circle is a mix of offensive and defensive based attack to seperate and defend him from his opponent. This is his strongest attack and can last up to 5 min if defenses are
not employed as he makes his, or his parties, escape typical time lasts 1 min.
A total of 10, 5, or simply 1 cross like, flaming speer's burst from the ground to create the circle, line or personal shield. From the middle of the cross (where the horrizontal and vertical connect.) can throw soft ball size fire balls as the last part of the attack. The attack can only shoot 10 balls. 1 for each 10, 2 for each 5 or 10 for each one.
Fire resistance:
This is his natural ability given to him through his mother. This ability allows him to walk though the hottest of fires without a single burn thanks to an oil created on the skin and in the fur. Because of this he must drink water on a regular basis and is commonly seen with a tankard or large water skin.
OOOH Tay, so far this is what his powers are to detail. All his powers have conditions and his main power has many manipulations due to the special time he's spent on it. Its pretty much his special attack. In growing he may find one more like Fire rain or something but that wont be for at least another year of manipulating his strengths. OR if Kara or another flutter teaches him how to fly better he may just pull off a simple sky agility.
I hope this is sufficient and if theres anything I can do to improve him or if you have any questions or problemos let me know