The reason was ever since the donor option has been added the players popularity in our server had a loss. Maybe this was one of the reasons why so then to stop these guys from begging or asking for the donor weapons so we decided to put them for the diamond crate. I think it's also selfish if we don't give these guys a chance to hand one of those too.
Since then the donor weapons are equally balanced, if we are gonna compare Thunderbolt and Destroyer i think both are great but then the thunderbolt does more damage like advanced with a very slow reload/charge.. while the Destroyer has a double or triple damage hits and u can fire it with 1.4-ish seconds.
The Pulse rifle is a fun gun to use it's just the buffed alternative version of the Plasma rifle, the Plasma only has reload for a fair use ( also with unlimited ammo) since it has a high damage with rage and incendiary bullets while the Pulse gives x1 damage, has secondary firing attack option and no reloading comparing to the Plasma.. but later on it gets boring (for me).
Vulcanus-XI is a good auto shotgun for crowded zombies around you since all the special shotguns gives those powerful knockbacks and damages like the Balrog-XI and Skull-XI. The Vulcanus-XI deals with high damages but comparing to Balrog-XI is a bit confusing when we compare these both which is better and they both have 2 Different Secondary Firing attacks like the Vulcanus for blue flame shells and fast firing mode then the Balrog for Spitfire mode while the Skull-XI has a zooming scope & only deals with higher 'advanced' damages like the Vulcanus.
The difference is that the Player skills like us make the game changes not the weapons.. Sometimes the weapons too but what matters is that our skills make it different. On the other hand, some weapons are still gonna need some tweaking and fixing right now.