Wieldiest refers to something that is easy to manage, carry or handle. Therefore, antonyms to wieldiest would be those that describe something difficult or uncomfortable to handle. The first antonym that comes to mind is unwieldy. This means something that is unmanageable and difficult to handle due to its size, weight, or shape. Another antonym is clumsy which describes something that is awkward or difficult to move. Other antonyms for wieldiest include bulky, unmanageable, or troublesome. These words are used to describe objects that are hard to hold or move, making them inconvenient to handle.