How to make animations for two objects? I have a sword and then a slash effect thing that trails behind it. The effect thing looks like this. I'm using the animation data tab in the NLA editor to create different animations for the sword such as holding, swinging left, swinging down, etc. I want the slash effect thing to not be there unless the sword is actually being swung, and like get bigger until the slash finishes and then shrink back to nothing. The problem is, when I insert keyframes for the effect thing, which is a separate object from the sword, they apply to all animations, so the effect thing will be in the same place whether the sword is being held or swung. Is there a way to associate the keyframes of the sword effect with the actual sword?

Pictures of problem. If I could just get the keys for plane.001 and cube to be  seperate from each other, I would be fine.
I figured it out. You just have to use armatures. What this means is:


create an armature from the create menu Shift+A.
position the bones in the Edit mode.
switch to the pose mode, shift+RMB click on each object and its corresponding bone.
press P to connect them using "bone" from the parent menu. 
finally animate the entire armature.