Just thought I'd share what I think I've figured out about discord training - and I think this applies to both pets and players. When you discord a skill and train it, it still gains at the rate it would gain at if it was not discorded. The only advantage is that you can train against lower skill level actions. By this I mean if your dragon is at 110 tactics, your shadow elemental would normally need to have at least 90 tactics for you to gain off it (that number may not be entirely accurate, but I think it is close). However, if you discord your dragon down to 90 tactics you will be able to gain off an elemental with a tactics skill of 70 or higher. The same kind of thing applies to a player training magery. Lowering your skill with a mage weapon doesn't mean you will gain skill at a faster rate than you would with your normal skill, but it will allow you to gain casting lower level spells, which require less mana, and cast faster, so there are benefits, but the gains per skill check do not change.