[video=youtube_share;hktzM6_j-tg]http://youtu.be/hktzM6_j-tg[/video]
Edit: Crappy video my kid took last weekend .. poorly framed...
There are heavy duty sharps protection gloves that are available. I was in a REEF lionfish tournament and as part of the entrance fee, they gave each team a pair of these gloves. I assume they work well for protection, but I found them too cumbersome for my liking. I've not handled a lot of lionfish, so take it for what it is worth..
I know that some people use safety shears to trim the spines underwater... this is only necessary if you are going to keep the fish to eat and want them in a bag or something. If you are going to do this, I suggest a multi-prong tipped pole spear because it holds the fish very firmly if it was shot in the head and gill plate area. it can not spin around as they can do if shot with a single shaft. Trimming the fins is easy, when the fish is immobilized by a multi-point tip. There is no reason to touch the lionfish.
If you are going to shoot them and then leave them on the bottom, there is even less risk of getting your hand in contact with the spines.... so less need for super heavy gloves... You just scrap them off the spear by using a rock or something on the bottom..
I've shot prety many lionfish with the multi-prong tip and any decent head shot pretty much kills them, so I've never felt the need to try to stab them with a knife afterwards.