In Tier 5 Vanguard (both Paladin and Fighter) Shield Rush is bugged.
The only requirement is that a shield be equipped, but it appears as though it is coded to require a melee weapon in the main hand. I can Shield Rush with a scroll in the main hand (and while it has been a few years I have beaten entire dungeons to death with a scroll), but not with a returning dagger.Shield Rush: While shield equipped, Activate: Rush forward in a line, delivering a shield bash to every creature hit.