One under appreciated aspect of enchanted weapons is low maintenance; he isn't even going to have to oil that blade to prevent rust even after all that time underwater.
... but he should probably ask his DM first, just because. ;)
Grrr... had this in my cart with 30 mins left on the sale. Got distracted by other goodies on RPGNow, and when I went to check out... The sale was over! Grrr... Thanks for posting this, and everyone learn from my mistake! ;-)