How do you maintain a knife?
That really depends on the design and materials. All knives have
to be sharpened now and then, which is an art in itself :). Then if
the blade is not stain resistant, it needs to be wiped dry after
every use, and preferably oiled as well. Folders need cleaning
(easier with a flow-through design handle) and the pivot a drop of
oil. Mostly that's it.