This is because, if you've dealt combat damage to a player with the Hope of Ghirapur, it can be sacrificed, preventing that player from casting noncreature spells until your next turn, causing serious headaches for any deck that revolves around any card type besides creatures
For a complete look at the set, you can check out the Duskmourn: House of Horror Card Image Gallery
The good news is that there are reasons to be optimistic about Mirrormade's future, especially with the return of Theros in a few months
A creature with a particularly powerful enter-the-battlefield ability will love this equipment with any equipment-based commanders like Syr Gwyn, Hero of Ashvale, or Bruenor Battlehammer to help protect them from removal spells
I really like how well she works alongside a card like Lashwrithe: sacrifice the equipped creature to get a number of 2/2 Zombie tokens equal to the creatures power plus the number of Swamps you control