Why is this the answer?

The answer is lock because this clever riddle uses secret words to describe how a lock works with a key. It paints a picture where the lock is like a strong, brave object that follows the key's command. Let's look at the clues one by one! The first clue says, "A dagger thrust at my own heart, dictates the way I'm swayed." This sounds dramatic, but it is really just talking about a key. The 'dagger' is not a real weapon, but the key that you carefully push into the lock. The 'heart' is the keyhole, which is a very important part, right in the center of the lock. When you push your key in, it is like a gentle 'dagger thrust' into the lock's heart. Once the key is fully inside, it takes control, or it 'dictates the way I'm swayed.' This means the lock has to move and turn exactly how the key tells it to. Without the right key, the lock will never be swayed and will stay completely still. The second part of the riddle gives us more detail about how the key is used: "Left I stand, and right I yield, to the twisting of the blade." Here, the 'blade' is the bumpy, specially cut part of the key that twists inside the lock. When you turn that key to the left, the little pieces inside the lock move so the door stays tightly closed, or 'stands' firm. This is the lock doing its job to protect what is behind the door. But when you twist the key to the right, those same little pieces move into the open position. The lock then gives in, or 'yields,' to the twisting motion of the key, and the door can be opened. The lock's whole purpose is to hold the door closed, and only the key's special twist can make it let go. The whole riddle is a wonderful way to think about a simple tool you use every day. It makes the lock seem like it has feelings and a mind, describing its important job of protecting things. It shows that even a small action, like the turning of a key, has a big power over the strong metal of the lock.