For speed you might want to try a dual dagger- a single hilt that splits into two separate blades. It could symbolize deoxy's speed since he is moving so fast you can't tell how many of them there are.
To be honest this is the first time I've even heard of Gijinka so I'm not really sure what it is but the Deoxys things you made so far looked awesome. Though maybe something like Rollerskates or something? since they seem to be something you could hold or wear. And they would make you move faster.