Adding custom text to a Word cross-reference field
Solution 1:
{ REF _Ref394485517 \r \h \#"'Section '" }{ REF _Ref394485517 \r \h }
If necessary, change the space after "Section" to a non-breaking space.
(NB, it can only work if the numbering contains at least one digit, e.g. a numbering style A.A.A would break this. AFAIK 1.2.3 etc. are OK even though they are not well-formed numbers as far as Word is concerned).