Slinky shoulder guards for a blanket, and belly protectors for spurs!
Curious as to why spurs are a necessity.
Rolly spurs, the roll on the skin instead of rubbing against and still work well.
Equifit has a great belly band that can protect your horse from spur marks!
Blanketing interferes with the horse's natural defense against cold because it flattens the hairs which are supposed to stand up to trap body heat.
For the blanket, you can purchase a shoulder guard. They are meant to prevent rubs. Also make sure the blanket isn't too loose or tight.
For the spurs, something that really helps is keeping the horse as clean as possible. This means they're won't be excess dirt/skin/hair particles to rub between the spur and skin.
Another fix is putting Vaseline or detangler on the spurs so that they slide more on the horses sides and don't catch (some people prefer detangler because it isn't sticky like Vaseline).
There are also ends you can buy to put on your spurs, but I find they make the spur less efficient and you end up just nagging on the horse.
If you want the issue to go away for good you could replace the spurs with a dressage whip. They are more effective than regular crops, and can be used without changing the contact on your rein.