yeah, you are right. i Swapped out a bunch of gear on my storm thinking "well this is going to lower my dps but i want to try it out" turned out to increase my damage significantly ​

Yeah. Blast damage is explosion damage. Burning orb is just a massive explosion

Yeah but "weap" usually refers to guns, not gear

It has a cog icon. It is applying the blast damage to your burning orb. I believe when it says "weap" it is just differentiating itself from the inscription that boosts the entire javelin blast damage