D-2 is a pretty tough steel. If the tip broke while he was cutting with it, that would indicate the blade was improperly heat treated and tempered. If he was doing the ol' screwdriver trick then that will happen on just about any knife. If just a bit of the tip broke off, then contact a local maker; there must be at least one around. Re-profiling it and re-sharpening isn't too much of a job. The maker might have a bit more problem if a more substantial portion broke off, and the knife requires a major re-profiling/sharpening.
