The hilt of a keris is referred to a "ukiran" in Java, which means "carving". In the Malay Peninsula itself, the hilt is more commonly referred to as a "hulu".
Like the Warangka, keris hilt shapes vary by region and so are good indicators of the origin. However, given that the clothing of a keris may be changed often over its lifetime, and the parts at different times, it is sometimes the case that the hilt and sheath do not match. This is also done deliberately for personal expression.
Hilts can be very elaborate and they are much prized by collectors, even without a sword attached! Hilts may be made from a wide variety of woods, ivory, horns, precious metals, bones and more.
The general shape of a keris hilt is often figural, and symbolizes a diety in a squatting position. Figural dieties may have features that are anthropomorphic, zoomorphic, or floromorphic.
For an excellent overview and pictures of the wide variation in shapes of Ukiran, go here.