Shadowrend is one artifact with two forms. The Shadowrend Creation lets you choose whether it is a greatsword or a battleaxe, and you can swap later. It first appeared in Shivering Isles.
How to get it
Go to the geyser pool northeast of The Atronach Stone in Eastmarch (quest: Through a Glass, Darkly). Try to take the weapon, and your own Shadow appears to fight you. Defeat it and pick the form you want. You can return to the same spot to switch forms.
Enchantment
Makes the target 15% weaker to magic for 30 seconds. It does not stack with itself.
Stats and handling
- Greatsword: 25 damage, weight 23, value 2500.
- Battleaxe: 26 damage, weight 27, value 2750 – it looks like the Daedric battleaxe from Oblivion.
Both forms beat a Daedric Greatsword or a Daedric Battleaxe in damage and use the Two-handed skill.
Smithing
Improve it with an 
Ebony Ingot. It needs Arcane Blacksmith, and Daedric Smithing gives the best improvement.
Known issue
According to UESP, the weakness to magic does not actually raise spell damage without the Unofficial Creation Club patch.
Strengths and weaknesses
- Strength: top-tier damage in your choice of weapon type.
- Weakness: the enchantment is bugged in an unpatched game.
Tips
- Choose the greatsword for faster swings, the battleaxe for bleed perks.
- Spellswords get the most out of it once the bug is patched.
Added by the Shadowrend Creation, part of the Skyrim Anniversary Edition. Details checked against UESP and summarised in our own words.
