During the poor weather most of my training takes place in a small kitchen.
I can comfortably adjust my Tai chi and Xingyi training but there is no room to swing a sword. I've tried doing my Tai Chi sword form with knives and short plastic swords but it never feels right.
In the end I have found it best to do the form without anything in my hand. Instead I visualise that I have a sword in my hand which works for me and doesn't detract from the form. This also keeps the sword form alive for me during the times I can't train outdoors.