I ran into a similar problem with my French maid, too, I built her a duster, but how to get her to hold it? What I wound up doing was parenting as thgeisel suggested, but also getting her fingers all adjusted (not a trivial task!) I saved a hand pose. And then I decided to also let her hold the duster like a pencil, so I saved another prop with the different position (the parented props get saved with the position as an offset from the parent) correct for that hold and I saved another hand pose. Now an overall pose can be applied, then the correct duster, then the hand pose, it save a lot of work. I would think a spear should have a tennis racket grip and a spear chucking grip, at least.