Since 0.9 I noticed something odd regarding basic units design. As you research new techs, the AI automatically upgrades them with everything you researched that they can equip (meaning player troops included).
Example: Basic spearmen unit, costs only production to build. Research Charms at start of game, you can't train same spearmen anymore, as they cost crystal to train, since they are automatically fitted with monk robe, initiative boots and accuracy gloves. This does not affect your already trained units (ie: the spearmen unit you had when game started is not upgraded).
Am sure this is a bug, because pretty much any new troops you will want to train will require crystal and / or metal, which you may or may not have at that early stage of the game, plus will be confusing for new players who will notice they can't train troops anymore.