All though skateboards are a very hardy material your knife will require a bit of upkeep.
As with all natural timber products do not ever put these knives in the dishwasher, do not soak in water, dry them thoroughly after use and keep them out of direct sunlight these things will all cause the wood to expand and contract causing it to crack. I use 15 coats of a hard wearing specially formulated resin lacquer to coat my knives, this helps with the water resistance of the handles and is silky smooth to the touch.
The brass fittings will naturally patina off with time, I consider this a beautiful part of the ageing, but if you want to freshen them up again simply give them a rub with some steel wool, I recommend 0000 still wool.
I sharpen all my knives on Japanese wet stones before sending them out, these are generally at a17 degree angle. to ensure this edge stays sharp I recommend chopping on timber end grain butchers blocks or rubber chopping boards.