To get this trophy do you need to have all 15 artifacts on your person?

yes, there are 16, one is on a thieves guild quest i got all 15 but i only use the spellbreaker.

lvl 41
554 armor rating
feel like immortal [censored].
nord.
daedric sword and spellbreaker and dragonplate armor.

Do you need to complete all the artifact quests on one character, or can they be split across a number of saves?

You don't have to be carrying them all, just have found them all.


Depends, if you want the Achievement, then one character. If you just want to find them all, it does not matter how many characters it takes you.