Just started a new game with Altar, and since I had 2 shards in my vicinity decided to make them available at start. Then I went to Charms as I had 2 ancient libraries nearby.

Guess what, after researching Charms, I couldn't build spearmen anymore. It was requiring crystals. Why? Because the AI pimped them up with all the magical gear I had available through research, automatically (monk robe, initiative boots, accuracy gloves etc). Can't say am a huge fan of this design approach, it literally cuts some incentive from designing new units as you unlock new gear / equipment, and seems a bit tedious to have to redesign the basic units if you research upgrades, since there is no way to produce the upgraded version with crystals and metal when you just settled and explore nearby areas.