Hello,
I understand you want to train your physieke in order to improve your matrial arts, adding extra weith is not the wright way to go. but
most competition wapons or training wapons are way lighter then the real deal, so make yourself something blunted with the real weight (you might add just a litle, not mutch ..) and trai with it,.. allot! keep repeating the same movements over and over, faster and faster... improvemt comes from investment in tiome and effort, not from using a bigger weigth, martial arts are about combat ability , so you need to build a strong lean body.. thats fast slender and tough, not just big and muscular....
thats only my opinion ofcourse.. i'm only a green beld in judo, but pretty good in shoy lay fut, and i'v had training with staff (chineese wax wood for competition, seasoned hazel for training) and with the chinese broad sword.
Find yourself a teacher and put in the right emount of effort! and enjoy!!