Hilara,
for the latter question: choice of materials is entirely up to you and should be adequate to your defined intended use. There is no "prescriptive" normative requirements that define/exclude certain materials for your device.
In your specific case, it might be prudent to at least consider surgical steel according to ASTM F899 also for your handle, since e.g. your handle will most probably also require reprocessing: steel according to ASTM F899 typically withstands generally used reprocessing methods.
HTH,