I will give my opinion, even though it is not much more than a hunch...
I agree that the signature says Orrefors, but it must be made by a "beginner": first a smallish o, then a gap, then cursive rref, then a bigger O, then rs. Could it (the signature) have been made by someone wanting to "make it better"? Sigfnatures normally are much better "flowing" and often include a model number and/or some kind of code.