As per the latest patch notes, the Lifeblood spear heals every 5 seconds while being wielded, keep your inventory tab open while having the weapon in hand and you should see your character’s health going up every 5 seconds:
I have another post about this up. They say in the patch notes that they nerfed the time and it is only suppose to heal u once every five seconds, however, it is not healing at all, i requested more info on it( how much ut is suppose to heal every five seconds)