The Sepulchre of Heroes in the Blood Angels' fortress-monastery houses the tombs of many great warriors from the Blood Angels Chapter's glorious past; each swathed in a highly decorated shroud depicting their victories. In battle, these shrouds are carried proudly aloft like banners, installing [sic?] the Blood Angels with a deep sense of courage and self-sacrifice. Any Blood Angels unit with a model within 6" of a Holy Shroud will ignore any negative modifiers to their Leadership when taking Morale checks (eg, penalties for being below half strength or outnumbered in an assault). In effect, they always make these tests using the Leadership characteristic on their profile.
Holy Shroud
Source: Codex: Blood Angels, p. 17