Artifacts and their properties.

Armageddon's Blade and it seems there is also the Ice Blade. Later, I know there's the Mage's Cauldron, which seems to accelerate mana regeneration.

When I read that, I thought the Ice Blade was the "Thunderclap" sword, but after reading the following posts, I remembered that there was indeed an "Ice Blade" in Chronicles, and it's not in the regular Heroes game.