Just because they can both be used to indicate when something started does not mean that they are interchangeable - there are patterns of speech and nuances. "Since" is usually used with a specific moment in time - if you say "since birth" it implies that something changed at the moment of birth (for example the baby is not genetically blind, but an accident during the birth resulted in blindness). "From" is less precise about the time, and from this we understand that the person has always been blind, as opposed to from the specific moment of his birth.
I would never say "He is blind from from birth." That makes no sense. The birthing is always a past preceding event in relation to any following awareness of his blindness. It doesn't even sound like English to me.
I probably would not say 1), but 'blind from birth' can be regarded as an adjectival phrase which describes a certain condition. In that sense "He is blind from birth" is a normal sentence with the meaning "He is congenitally blind".
To me, "He is congenitally blind" means "He was blind from birth/He's always been blind", and descriptions and definitions of this permanent condition have to arrive in new sentences with different tenses.