Looking at the charts, it is 'standard' ILS type, but at a 6 degree angle. It is not lined up with the runway and requires visual manoeuvring for landing as said above. Innsbruck has an approach (from the west) which has
no glidepath (and passes well south of the airport, for visual manoeuvring) and is thus called a Localiser/DME approach. I assume it is the presence of a glidepath at Sion that produces this terminology.
There are, doubtless, experienced Sion operators here (not sure I want to be one
) who can give you the full story.