Weights vary for ponies of that size, especially since there's so many breeds. I would go more off of what breeds your horse is rather than all horses that size in general.
I think my 14.2 gelding is between 850-900 lbs. that's what I THINK though...so you should go by Alice's comment.
My arab x Aus riding pony who is 14.2 is around 400 - 500 kg