Rayleigh's Sword

Ahoy, again it's none other than me, Blackendedsoul. So today's topic is...Robotman Takrabhoom aka Gakra-san! Nani? Just kidding, Robotman Takrabhoom aka Gakra-san is not so trifle to be discussed in this blog so cutting the crap I am now cutting to the chase. The topic is as the title declares, "Rayleigh's Sword". Now Rayleigh as we all One Piece fans know is a very important figures in the One Piece world. Both power and reputation-wise. Also Rayleigh has proven himself to be a proficient swordsman at the least if not a master swordsman. Now here is the thing I am concerned or to be more precise curious about. As we know that there are the named swords which are normally superior to ordinary swords and are commonly used by the more powerful or competent swordsmen, thinking from that point of view it seems to me logical enough to conclude that a person as great as the Dark King is supposed to use nothing less than a named sword. Now here is the crucial part, we first saw Rayleigh using a sword while battling Kizaru. At that time he was using a double edged long sword if I am correct. However after the time skip when he stopped the marines from chasing Luffy he wielded another sword, it was a katana or something of similar sort, that is, with a single edge with a slight curve. What could be the reason behind it? Does Rayleigh has/owns more than one sword and carries them alternately? Or did he lost his old sword in a battle/occasion? (Unlikely in my opinion because if he indeed lost it it was probable for him to replace with a similar sword as he is supposed to more proficient at wielding something similar to his previous weapon). Also what was the grade of his old sword and what is the grade of his new one? Any idea's any one?