I would understand if you agree with
@Mary Poppins . But if you can't or don't want to return him, here's my two penn'orth!
Last year at the beginning of April I got my new horse, Sid. He's a 14.3/15hh chunky cob gelding and came labelled as a schoolmaster, unflappable, etc etc. He lives out 24/7 with another horse in a field opposite my house. I am very happy with him and think he is great, but I really took my time getting to know him. It was 6 weeks before I could get a saddler out to approve my saddle fit, so I could only ride him during that period bareback (on my bareback pad), and I didn't try that until I had had him for more than 3 weeks.
In those 3 weeks I got him in every day for a groom and a feed (and he was a monkey to catch at the start, as he had never as far as I know lived out and he absolutely loved it) picked his feet out, tried to figure out how to treat the scabs under his feathers, and took him for lots and lots and lots of walks. Everywhere I wanted to hack later, at least to start with, I walked him. This meant that by the time I had a saddle and could hack him out, we had got to know each other, he knew the area, and he had started to feel confidence in me. If you're interested in how I approached it, read the early sections of my diary
https://www.newrider.com/threads/sids-diary.256400/.
Even after all of this, he is still a horse, and horses react to things. He hates high winds, and I would think three or even four times before riding him out in a high wind, though I would walk him in hand. Change blows his tiny horse brain - when he got a new companion, he was vile to everyone except me for an entire week and would only let me catch him. He reacts to unusual or new things when we're out, usually by planting. He is grumpy and opinionated, and since I got a sharer he has started to nap and try to say whether he will or won't go in a particular direction. I'm not having any of that, but I had my RI give me a lesson today on how to deal with it firmly and ethically - I'm about to post about it.
To summarise, I don't think horses are ever "finished" or "bombproof". They are always going to be flight animals, liable to react if their environment changes or they have new handlers or a new routine. Your Wilfred (great name BTW) is in a new home, living out for the first time in ages, with new handlers taking him out to places he has never been. No wonder he is unsettled! Add high winds to that and you have a recipe for trouble. My suggestions:
- Take it slowly. If you spend the first few weeks getting to know him, not riding him, it's time well spent in my book.
- Be with him lots. Groom him if he likes it, bring him a carrot when you come, bring him on to the yard for a feed, paint his toenails, plait and unplait his mane and tail, tack him up and take it off again, just do things with him.
- Take him out to get to know your area. Lead him if you like, or long rein him if he knows how.
- If he is spooked, as @carthorse said, don't hang on tight to the rein. It's the instinctive thing to do but can lead to running backwards and, as you found, rearing. Do you have a neck strap? Mine saved my bacon several times on my first pony, who could be difficult when the mood took him.
- Finally, be kind to yourself and your daughter. You have been scared and bruised (emotionally and physically!) by your horse owning experience so far, so no wonder you're feeling anxious. I always get butterflies before I go out for a ride, although when I'm actually out I don't have a care in the world - look after yourself, remind yourself that you don't have to do anything you don't want to do, and if you just want to walk him in the yard or ride him in the field for a bit, do that.
I have always been a great believer in getting help. If I were in your place I would get my RI to tide him out for me a couple of times to assess him in his new environment. Maybe there is someone at your yard who will help you?
In any case, I wish you the very best with your new cob and cross my fingers that you get past the teething troubles and have many happy years together.