Bison
First of all I'm no expert on SS daggers (SA is more my field). The dagger itself looks good to me - it's an early (1933-35) Rich ABR Herder blade made in Solingen. The roman numeral 'I' stamped into the lower crossguard is the checkmark by the SS uniform distribution centre in Munich. 'II' was Dresden's and 'III' was Berlin's. Nearly all copies or faked SS daggers bear no manufacturer markings or RZM markings. So I'm sure the dagger is good.
The mismatch of dates (as any RZM issued elements were later) is well known on SS daggers. As the owner was promoted or damaging the existing scabbard the supply of later chained scabbards to replace the earlier scabbards was standard. Sometimes the existing scabbard was updated by fitting the chain or sometomes a complete scabbard was purchased. The whole dagger, at that time was an expensive item (as it is now).
The chain, however, I'm not so sure about. There were two types. Yours seems to be a type II with chamfered chain links from the chain into the cloverleaf or 'Woton Knot'. On these type II chains I have only ever seen the last round openings over the clip solid - that is with no hole through to the clip. Only type I chains have this hole through which you can see the manufacturing mark. Yours looks to be an RZM mark where originals I have seen bear the DRGM mark. I'm sceptical about the chain as it has both type I and type II elements but as I say, I'm not an expert on SS daggers.
Best of luck, would be nice to hear any more on this.
Spaz