I dont know if u play on f2p or p2p, but if it's the first one...The egg decrease your damage to compensate your runes level. Loosing xp upon death I think it could be linked: in this way u don't take so much advantage in being stronger, killing other players. If u want not to loose exp then you must go to the NPC and go full power.
So you have all the possible damage for your char, don't loose exp upon death and you can exp with PvP kills.
In Italy we say "you cannot have the wine cask full and the wife drunk".
Sometimes it's a pain, but I think it's needed.
Instead, if u don't play on f2p but on p2p ..in this case this debuff have no sense