Hmmm that looks like a luma/problem. I checked the texture and the blacks 0,0,0. It'll probably be effecting the grenade too. Basically the luma texture are meant to glow in the dark like a led, gl_lumatextures "1" enables them. Though they can be turned off in a server somehow, maybe the server turns them off, but I've never seen them black before.
worst comes to worst just temp delete grenade_0_luma.tga, missile_0_luma.tga, g_light_0_luma.tga those are the only ones that should give you black issues
worst comes to worst just temp delete grenade_0_luma.tga, missile_0_luma.tga, g_light_0_luma.tga those are the only ones that should give you black issues