There's your reason mate, I'm also too looking for idea's. I'm wanting to make something cool.
If an add on maker wants to make a cool add on, the last thing they should be doing is thinking about weapons. We have enough crappy weapons. There is no possible weapon anyone could think of that would actually be cool and add an interesting aspect to Blockland.
We already have a weapon for every single purpose and then some, look for something original if you are an add on maker looking for ideas.
Edit: Think about who everyone's favorite add-on makers used to be. Trader, Space Guy, ect. Why? They were sort of the innovators of the Blockland community. They made new and original content that added something to the game that wasn't just another pretty model that shot projectiles.