Netty, he is perfectly natural in Western tack and a lovely horse.
He looks to have a rather short back, so having a shorter pad under that saddle would look better in my opinion. The blue is too loud for me and makes the saddle look like an "island" on his back.
I think a black blanket with some stripes or some other decoration may be great, and if and when you have the money, a black bridle with some silver accents, and get one with the wider cheek pieces. He might look cool with a decorative fly whisk under his chin (hanging from chin strap.) it would kind of mirror his full tail.