Handhold for assisting to get up on to the wing on the left hand side of the fuselage.
There are also pictures of W25's original handhold, no parts of which were salvageable due to age related corrosion. It did serve as a perfect pattern to assist with it's replacement.
You can also see a form block used to make each of the end caps of the handle surrounding.
In thise picture you can see the new handle on the bench.