As currently playing a 1hshielder, backpedalling 2h/polers are the worst enemy to face. But I dont see a need at all to nerf backwards running speed, if they outrun you backwards they have a higher athletics skill and should be able to utilze that.
Just try and not play into there game, recently just got a pike for a fast switch back and forth to get em back inn.
Oh and shielders get stunned, atleast I get often from barmaces, same as manual, have to take another hit=/