not necessarily

Most likely they use a standardized texture size. As Sage weapons have only 4 times the same >small< model while scythe have at least 3-4 times the amount of stuff going on that needs to fit on texture sheets, therefore details end up having only 1/4 of the pixel count on the scythe, therefore it would makes sense that one of the weapons comes out alot more blurry than the other one