bokuto is literally, wood sword, but I suppose you can leave this romanized if you want (it's not a 'bokken' if that's what you're thinking)
hakugin (白銀) is indeed silver (literally, white silver)
zanma is, if it's the word I'm thinking it is (秋刀魚), a type of fish.
kongou (金剛) is diamond, and is also Indra's weapon in the Hindu faith (was this the Shiva Edge in Woolsey's?)
tenou I'm not too sure on, possibly Heaven/Sky King (or you could just leave it as heaven, I suppose)
yasha (夜叉) is a female demon
suzaku is the red phoenix of the east in chinese mythology (and astronomy)
(and yes, I agree with leaving Yasha and Suzaku romanized, heh)