Just aim the head, you win the 1v1 easily with a good aim.

You do not want to duel Maeve as her combo WILL one shot you. Stay away from where she likes to play unless you have an ally who can kill Maeve first with you.

If you have pounce available don't be afraid to engage Talus. Hitting both daggers, pouncing and hiting both daggers again will finish off Talus before he can react.

Try to stay out of his line of sight, and find where he will teleport back to so you can surprise him. Be prepared to hide quickly, because you can die very quickly to him. Try to pair up with others to minimize dmg taken and to kill him quickly.