Is there something about her mythology I'm unaware of? Why would a bottomless dipper be her weakness?
Apparently, a ship ghost asks the men aboard the boat for a ladle, and if they make the mistake of giving her one, she will use it to pour water into the boat until it sinks. I suppose if they refuse, she just sinks it anyway.
But if you give her a dipper without a bottom, she will try to sink the ship with it despite being unable to scoop up any water at all. Thus, you're safe.
Murasa apparently came to thwart these wise and prepared men by acquiring her own permanent dipper, so that she never needed to ask for one. (Though the one she has is also bottomless?)
Whaaat?! You use your HANDS for a dipper!?I've buried countless ship ghosts, posing as a fisherman! How could one such as I—!!Aye, 'tis a bottomless dipperrrr!!LoooomTossPlapSshlff...KAPLASSSHTh-that's...!Hee heeGlub BlubHeh heh heh. Even ship ghosts are constantly evolving!