Getting hit by multiple snipes leading to instant death is due to lag. It happend to me quite often in the past. Beware of people using this skill from a distance, watch the surroundings for bow spammers.

I like to use a bow myself and am amazed about the ridiculous lag sometimes allowing me to kill a players without him/her being able to respond. Kill and get killed in Cyrodiil is often a matter of change.

Usually the guys who can 1-2 shot kill you with snipe are the glass cannons, once happened to me, I died, second time he ambushed me I was ready went up in his face and smashed him in like 10 seconds, he had low stamina and was a stamina Nb. Prolly all his points/armor into weapon damage/crits.