They don\'t represent lost battle brothers, nor are they battle honours (although they may be awarded after a battle) A purity seal indicates that the person who owns it, or the armour that it is affixed to, is pure of mind, spirit, purpose and body. Essentially marking them fit for battle. Often containing an oath, or valediction of the wearers purity. 1. No, the warp is localised and limited to our own galaxy, it does not extend beyond our galaxy. 2. Not quite, although the Eye of Terror is the main focal point for daemonic incursions into the materium, Chaotic forces of a non daemonic nature (Traitor Astartes, Traitor Guard etc etc) are usually free to roam, although any forces stationed in the EoT have to breach the cadian gate in order to expand further. No, because not only of the vast gulf of space between galaxies, but so far, galaxies are either dead, emptied by the Tyranids, or reportedly full of Orks.