Need Help Understanding...

So I'm sorry if this was answered somewhere else but I couldn't find it. And also, this isn't a complaint thread….

So how do I make my level 75 archer strong again? Is there a build/armor that helps? I have what used to be full endgame and Bob's Mythic Bow. I'm trying to not look at them like I used to, but I wasn't expecting to need multiple hits to kill a level 40 mob or die while doing an easy lvl 43 (or so) quest. Now I know to have health pots with me even in low level areas, but is there anything else? I'm sure once I figure it out the new system will be awesome but it just might take a while.