What do the stars mean in Zombie Gunship Survival?
It seems like there is no difference in stats.
Three stars:
Two stars:
My experience has been that the stars represent a cap on the level. So a 1-star weapon could go up to lvl 10, but after that it needs to be Fused to become 2-star, and continue leveling.
I haven't tried leveling to 20 yet, but I suspect 2-star weapons will cap at level 20.