Rayleigh has kinda a different sword in the current chapter as we see 20years later when he show it.
Old Rayleigh:
And Rayleigh sword in the past:
Different swords, the question is now what happen to his sword which he had in the past. For sure it don´t fit to Shanks current sword, the shape of the two swords are different. Even Shanks and Roger sword aren´t the same as judging by this panel.