Think and discussing grenades and other throw things I believe we can make depend on the players style. If your guy is a smashball champ with excellent athletics let him use athletics to toss his grenade, spear, javelin, dwarf. If he is a guy who learned in boot camp how to place his grenade properly let him use Ranged (Light). This makes sense from a logical standpoint and relaxes a little of the brawn close and agility ranged part of the game. The game has many skills and only half are really useful most of the time.
Administrator- Daily Dose RPG
Game Master- DarkStryder EotE
Dungeon Master- Scales of War 5E