Cheesy trick: Use bracelets (I don't remember which book it is). The base cost is 1000 gp, then you can enchant it as normal weapons (+1, +2, flaming, etc...), but you always need to enchant both, doubling the costs. You put on the bracelets, and all the bonuses counts for your unarmed strikes.
Get two +5 defending bracers, put them on, switch all the bonus to defense (a total of +10) and then use your normal weapon of choice. You can use these with normal armor, since they stack with armor bonus.
I don't know if a DM would allow it, but as written, you can use it, as defending weapons don't require you to actually be fighting with them.