Grenade, Flash
This grenade, when it detonates, causes an ionic discharge that disrupts sensory equipment and temporarily blinds those within the area of effect, and creates a flash visible at a distance.
Any character within the area of effect must make a Willpower (not Fortitude) check against a DC of 15 to avoid being blinded by the flash for 2d6 rounds. Characters wearing Flash Goggles get a +2 to their saving throw. Characters with Low-Light Vision have a -2 to their saving throw if the flash grenade is used in an otherwise dark room. Characters using Low-Light Goggles have no bonus or penalty, since the automatic light-adjustment cancels out this sensitivity, but not enough to provide any additional protection. Stormtrooper helmets include flash protection that gives a +4 against blinding from flash grenades. Other gear may provide special bonuses.
Blinded characters cannot see at all, and thus everything has full concealment to him. He has a 50% chance to miss in combat. He has an effective Dexterity of 3, along with a -4 penalty on the use of Strength- and Dexterity-based skills. This -4 penalty also applies to Search and any other skill check for which the GM deems sight to be important. He cannot make Spot checks or perform any other activity (such as reading) that requires vision.
Grenade, Ion
This is a grenade form of an ion-based weapon, causing an ionic discharge that scrambles delicate circuitry. It can be set to either cause damaging effects against electric circuitry (in which case it deals damage as listed), or else it can be used to "stun" droids (in which case any droids in the blast area must make a Fortitude check against a DC of 15 or be stunned for 2d6 rounds). This has no effect on organic targets, unless they have electronic components (such as cybernetic limbs).
Please note that the use of an ion grenade may have unforeseen side effects in highly technological environments, such as on board starships. (They tend to do nasty things to gravplates, and are generally not good to use around magnetic field generators and containment fields.)