what's the bosses i have to kill to get ally lvl 4 and 5? or how to get the items feather or valor and the other for lvl 5?

For lvl 4 you will need to take the quest Prove Your Courage from the Hierarch in the Varka or Ketra Village and kill the raid boss Varka's Hero Shadith if you have ally with ketra or Ketra's Hero Hekaton if you have ally with vaka silenos. For lvl 5 you will need to take the quest Slay The Enemy Commander from the same Hierarch and kill the raid boss Varka's Commander Mos if you have ally with ketra orcs or Ketra's Commander Tayr if you have ally with varka silenos. You take the item from raid bosses if your party does last hit. When you kill the raid bosses and take the item get it back to the hierarch and you will get the necessarry item to lvl up the ally.