Regarding artifacts, I would add the Blade of Cold (not the one from Heroes of Might and Magic III), which increases attack and defense by 3 (like all swords in the game) and the chance to freeze the enemy. It's strange that they didn't add it; there's a fire sword, a dark sword, and a light sword, but no ice sword.

In the official expansion, Armageddon's Blade, the Frost Hammer artifact appears, which allows you to freeze an enemy for several turns. There is also a potion of cold, which gives the hero the ability for one battle, similar to the Ice Demon, whose actions, like the Frost Hammer, freeze the enemy. I'll say even more – there is a spell in the magic of Haven that freezes an enemy for 2 turns. But this spell is not available in regular maps or for heroes.