If I understand your question correctly...
All offline training is sword/axe/club/distance/magic level + shielding. The difference with online vs. offline training (except for magic level) is offline training is 50% as effective as online training, and offline training is set as training against 1 opponent. This is fine except when it comes to shielding. The best way to train shielding having 2 opponents hit you. So offline training (having only one opponent hit you) means your shield training is only 25% as effective as online training.
TL:DR
All offline training increases shield skill, but only at 25% of what you can train online