SS dagger - RZM 15/39 - Authentic?

[Vertas4]

Hello everyone,

 

Coming to you with an SS dagger which looks really good to me but I would need your help in identifying it's authenticity.

One thing which concerns me is the svastika, per some articles I found out that for the later versions it should be more thick and not as thin.
Or do you think that if this is transitional version, it could still be thin svastika?

 

Also do you have any experience with the black background behind the svastika?

Thank you very much in advance!