Shun knives use two types of steel: Takefu VG-10, and also their proprietary “VG-Max” steel, which starts as Takefu VG-10 as its base, but with higher trace elements. VG-Max is very hard (Rockwell C Scale = 61), and is often referred to as a “supersteel”. However, it is prone to chipping. Shuns must be sharpened at 16 degrees per side.
VG Max is so hard that I have to sharpen it using CBN (Cubic Boron Nitride) wheels and hone it with various grades of diamond paste. This results in Shuns being twice as sharp as when new. In fact, I have clients that bring me their brand new Shuns so I can unlock the full sharpness possible! Shuns are usually about BESS = 200 when new (see picture in the gallery of a brand new Shun parer with BESS=210).
The two special edition Shuns designed by Ken Onion pictured in the gallery are sold out. Market value is around $500 USD for each.
If you have big hands, try a Shun in person before buying. I think Shun sizes the handle clearance distance (to the cutting surface) for small Japanese hands.