Ok now the conclusion.
Cables are fine for both rear wheels. Pads are fine
- Get rear disks polished. 1.5hours time and Rs. 300 cost
- Bottom of the handbrake lever has adjustment screws, get ur handbrake adjusted from there 1st and then from the wheels.
Cable is pulling but even after maximum pull, pads of one wheel are grabbing the disk prior than the other, not letting the handbrake to pull more, hence poor braking due to brakes engaged at one wheel only.
Or they are not getting much grip as the surface of disks became so soft to resist. Polishing is required here.
Now ur saying, pedal brake is fine. Well pedal brake is operated by hydraulic system, so no matter how the pads are, how the disks are, it wud still be much better than handbrake as handbrake is a manual thing