How can you even tell who is doing the most damage overall at completion?
Pretty sure they calculated it manually with an abacus. It's kind of besides the point though.

I do not see much to do as a bard other than keeping straight shot and 2 dots up while weaving in CDs and repelling + blunt arrow.
Yeah that's about it really, keep your DoT's up, keep straight shot up and burn your CD's when you can/it's safe.

What you're seeing is pretty normal. A solid Melee DD will out damage a bard. Keep in mind you're not there just for DPS though. Also, yeah, the drop in iLvl would be making a difference too.