Oli,

Your scabbard is a Holler product. This scabbard type with the single reverse screw was certainly used by Holler when they were still producing blades with a tapered tang and their briefly produced 2nd variant x guard (1936 ish). In my opinion it is not inconceivable that this config on a small producer is possible. The Pack fittings are certainly earlier as is the grip but being a small producer Spitzer may have held them in stock for a while. From what I can see the tone of the components match. Although one might expect a slant to have a scabbard with two dome headed side screws it is not by any means conclusive to me that the dagger did not leave their factory exactly as it is.

If I understood correctly I hope this answers your query.

Best regards

War is when your government tells you who the enemy is.
Revolution is when you figure it out for yourself.