I'm having a hard time understanding the information that can be stored in a BLOB.
It's pretty self-evident that SHAPE_Area has a numerical value, but is the actual classification a BLOB or Number?
From the Layer Properties of this file geodatabase feature class you can see that SHAPE_Area is of data type Double. It is not stored as a BLOB.
If you are referring to a geometry when you say blob here, then for geodatabases, but not shapefiles, the area is dynamically updated when the geometry is edited.