Currently, Flash grenades are not worthwhile to take over regular frag grenades because of their standard fuse ineffective radius, and unassuming explosive animation. So, I suggest turning flash grenades into flashbangs. Something like this:
They do go bang, and they do have a flash. The problem is they have such a long fuse that they are near useless. If they had a standard fuse so they would detonate while people are in the blast radius it would make them 500% more useful.
Also need visual FX on affected targets, like Star Wars MMORPG has: (the white light around his head)