To get the Saber in Blox Fruits, start by reaching level 200. This is essential to begin the Saber Quest. Once you are level 200, head to Jungle Island and press five green squares to unlock the Saber Expert. After solving this puzzle, go to the center of the Jungle and find the torch.
Next, take the torch to Desert Island. Locate the abandoned house there and use the torch to enter. Inside, you will find a door leading to an underground passage. In this passage, you need to find and take a cup.
With the cup in hand, travel to Frozen Village. Look for a cave with an icicle and fill the cup with water. After filling the cup, find the sick man in the village and give him the water-filled cup.
Now, go to Pirate Village and talk to the rich man to receive a boss quest. Complete this quest by defeating the boss. This will reward you with a key.
Finally, return to Jungle Island. Use the key to unlock a hidden door and defeat the Saber Expert to obtain the Saber. By following these steps, you will successfully acquire the Saber in Blox Fruits.