This is the Takebera* bamboo knife, used for trimming, carving, shaping and cleanup the foot of wet pots. There are many ways to hold this tool. Just try different ways and find the most suitable one for you.
*The Japanese name of bamboo knife is Takebera. Bamboo knives have been the most widely used pottery tools by production potters in the Orient for centuries.
Dimensions: 8" L x 3/4" W