I'm not sure if you want to do this. The major advantage of archers is their range. Because of that, you can better snipe with them, and they don't overkill as much as slingers or javelins.  Don't forget their faster rate of fire, as well.

Maybe for cavalry, boats, and siege, but normal units are probably fine. I also think archers should do more damage, it seems like someone in game could get hit with 10 arrows and still be fine (with less health ), and still be charging

DE has implemented a "Civic Spaces" aura around the CC which reduces grain gathering by 50%. 

Well that's kind of what I was talking about, I don't think we (me personally with my limited experience) could make that possible.  But it could still be to your advantage because you aren't getting attack.

But let's say someone has a shield, the shield doesn't help them in the back, they would have to turn around. But then, not everyone has shield. Maybe people with a shield have -1 resistance from the back?