Re: care and feeding of wooden weapons
Know what type of wood you have. Most weapons are made of white oak or impact grade hickory. There are weapons made of exotic woods like teak cocbolo, rosewood, purple heart and composites! These are usually custom weapons since the material cost can be quite pricey!
I assume you are asking about how to care for either Japanese oak (shiro kasha) or American hickory. Both woods, if from a excellent grade, will hold up to hard training for many years. The maintenance is basically the same for Jo, Bokken (or tanto); however, you may wish to finish them differently.
Before starting out, examine the wood carefully. Shallow dings and dents from normal training are expected and can be handled with a re-finishing process. A skilled woodcrafts person should probably handle major damage, deep splintering or gouges found on the wood. But this would be the exception rather than the norm.
Start by smoothing out scratches and dents using a medium grit sand paper. Use a sanding block if needed. Follow this with a second pass using a fine grit paper. If you want to get fastidious do a third pass with super fine paper. IMO the later is not necessary. Wipe down the wood with a clean cloth or paper towel before completing the re-finish process with an oiling.
Boiled linseed oil is the most commonly used finish. If you are working on a Jo staff, this tool is designed to slide through your hands. If you mix a small amount of mineral spirits into the linseed oil, it will dry on the wood with a smooth slippery feel.
The bokken (and tanto) are designed to be held onto during use. If you make a mixture of linseed and tung oil (10 part linseed 2 part tung) the final result will be a "sticky grip" on the wood as your hands warm up the finish during training.
Using a rag, begin by dapping the weapon's ends first. This will allow for a deeper penetration. Liberally wipe the weapon and then let it set for 10 minutes. Wipe away excess oils with a clean rag. Depending on your climate, ambient temperature and humidity the wood may take a few days to fully dry.
There are some folks who use other oils and waxes. The aforementioned procedure is widely used and is effective. It's served me well for decades. Remember to use good safety habits like wearing eye, face and hand protection. Oils are flammable so take care not to get them close to heat sources and dispose of oily rags appropriately.
I re-finish my personal weapons twice a year. The dojo weapons get looked at more frequently and are re-finished 3 - 4 times a year. Large splintering and grain delimitation are the most common reasons injuries occur, so we keep everyone safe and reduce replacement cost by paying close attention to these weapons.
In terms of storage, if you use your weapons frequently (as you should) keeping them in a weapons bag stored bokken handle down should cause no problems. If they are left dormant for extended periods I would recumbent laying them flat and in a place out of extreme temperatures.