actually for a waterfind the surface of this sword is somewhat oxidized.
In General, subject that there was no contact with the organic material, swords are better preserved under water than in the soil.
some come "as new" from the water after hundreds of years, fe some of the viking swords found in the river Ouse/UK in Records of the mediėval sword/Oakeshott, and other Ouse finds which have been in contact with organic material totally excavated.
for a very good water preserved sword, see for example:
http://www.vikingsword.com/vb/showthread.php?t=9989
best,