Grabbed the kitchen weight and my fathers and my bokkens (somwhat dark oak and white ash) are both a little under 600 grams. But I also consider them quite heavy for fast practice (heavier than standard paired work bokkens) yet I like that. They're light enough to develop speed and heavy enough to develop strength and correct movement. Please don't forget that a real steal sword is usually MUCH heavier than our usual bokken (differently balanced too).
I have 2 jo's. One is very light, which I like for paired practice (speed!) it's only 250 grams, don't know what wood and another one is heavier (500 grams) which gives the feel that you can REALLY hurt someone with that if you want to.
Anyway if you do hard paired work then none of those tools you buy will last over a year so you can buy new ones
Jorgen