The utility that this duelist/ravager offers is amazing, you get a 50% slow, two gap closers, two stuns, a DOT that can outdps any bards heals(if u have enough damage), a buff that increases crit damage by 70%.
This is pretty much my 1v1 fights.
If its a bard or Guardian, use the ultimate that gives dot to your first skill, Spam those DOT's. Against duelist ive found, spam cross slash stuns and combos, when u get 3 stacks of cross slash, it should be over (kinda luck based here cuz dodge can be iffy, i suggest ACC).
Vs ranged champs,(kinda luck based too, i suggest 95% dodge) Spam your gap closer to get close, if u get close enough, stun>cross slash>stun(the 20 second cooldown one)>snowflower>combo if that doesnt kill them, just keep chasing them down with your gapclosers, save the ravager gapcloser if you really need to get close and the duelist gapcloser is on CD.
Havent fought enough ravagers to give you a suggestion
TLDR: GET LVL 50, SPAM DC Hard, GET THE PVP SET FROM THE BOXES(you can finish this set by lvl 52, with tokens), PRACTICE 1v1s(IN MIDDLE OF NAVEA), You will learn how to beat anyone 1v1 ^_^
As for 5v5s, IS THAT U RIOT? No balance yo