If there were any doubts of HTC HD2 having a plastic screen, then these suspicions should be thrown away as soon as possible. HTC HD2 has a glass screen which is resistant to knife attacks and sharp knife attacks for that matter. Shown below is a video, that provides proof of the HD2 being resistant to knife attacks.

Leatherman Supertool 200, which has all sort of sharp knifes was used to put the beautiful touch-screen phone from HTC on a knife attack test , and as you can see from the video, the phone comes out unscathed, much to the comfort of HTC itself as well as HTC HD2 owners.