Bleed Weapons are used to inflict heavy damage. The damage dealt is a percentage of the afflicted player's maximum HP, usually about 30% but can go up to 50% in the case of Priscilla's Dagger and Lifehunt Scythe. Attacking an enemy or player builds up their bleed meter, and when the meter is maxed the bleed status is inflicted.
Poison weapons will inflict poison on the enemy, which does damage over time. Attacking an enemy or player builds up their poison meter, and when the poison meter is maxed the status is inflicted. Some poison weapons actually inflict toxic, (those being the Gravelord Sword and Dark Silver Tracer) which does even more damage and reduces stamina recovery. Toxic buildup uses a separate meter from poison buildup, but both are based on the poison resistance stat.
Holy Property is obtained by upgrading a +5 weapon with the Divine Ember or Large Divine Ember, or is found naturally on some rare weapons. Prevents Skeletons from being revived in The Catacombs by Necromancers, and adds bonus damage against skeletons in The Catacombs, Mass of Souls in New Londo, and the bosses Gravelord Nito and Four Kings.
Dark Property is obtained by upgrading a divine weapon with the Dark Ember, or is found naturally on some rare weapons. Adds bonus damage against Black Knights and Silver Knights, and the bosses Dragonslayer Ornstein, Dark Sun Gwyndolin, and Gwyn, Lord of Cinder.