How to make an Olivia that's good as an actual unit.

Not too difficult. Wo Dao refined for Speed with a +spd iv(any bane that's not atk will do) Moonbow, Fury, WoM, Hone Atk, and a speed increasing seal.

Ruby sword can work on her along with Fury, WoM and some kind of Tactic or Hone skill in the C and Seal slots (+3 Spd seal also works) however this Olivia build should mostly be used against greens.

Try an Atk/ Bond skill with WoM and Close Def. Armorsmasher or Zanbato are great weapons. Olivia has low Atk but these weapons are the easiest way to circumvent it. I guess I know pretty well, Liv is my one and only 5-10 hero...

Btw, I use her for fun to defeat other Olivias in arena. She never lost so far.

I have a 5* +7 olivia that carries Killing Edge +spd, moonbow, fury, wrath, and atk tactic as the c skill and def tactic as the seal for my mixed teams, she also has infantry pulse for my infantry teams and a couple of fortify/hone skills to swap into the c slot for whatever else

at full health, I use her to bait greens and once she's down below 75% health, her moonbow is charged b4 initiating combat which allows her to initiate with 58 (48+10 from wrath) damage on top of the -30% to enemy defenses
that's paired with fact that once she gets counterattacked, her moonbow charges up again, meaning that the 48 atk stat really is just 58 (muh wrath) and she consistently ignores that 30% of enemy defenses whether it be her first initial attack or her follow up

fury hurts her bulk so she realistically has 2 comfortable matchups before she should just become a dedicated dancer

but lets be real, a dancer usually wouldnt be involved in more than 1 matchup without being in danger of a a physical KO so i feel like my olivia has her merits

I wish i had invested into a +spd -res olivia, but i settled for neutral IVs which is a bit less than ideal but it works

Pretty easily, actually. She's got a pretty good statline, I find.

Right now I have her at +ATK -DEF +7 unit. I use her in my arena core with Wo Dao+ (+Spd), Dance, Aether, Fury 3 or Distant Counter if I need more score, Chill Speed, Hone Attack or Attack Tactic, and Hone Speed. I want to switch out Wo Dao+ for Kadomatsu+ for better use with the rest of her team eventually, though.

She's a very flexible hero and (in my opinion) the best dancer. She's got a good statline, we have quite an array of versatile swords to inherit, she's the only red dancer and she can be merged easily, while the others cannot. (And I'm not too sold on Uror.)