Armour Lock was widely considered an over powered armour ability in Halo Reach. But at the same time, many Halo players used it. So, how exactly did 343 Industries reach a compromise that would satisfy both parties? By creating the Hardlight Shield.
The Hardlight Shield acts as a kind of riot shield, slowing the player down, but protecting him from incoming bullets. Word of warning though: it is vulnerable to a well placed grenade.