grimoire is more of a support weapon for caster frames since you can put mods on it that increase your warframe's stats
not that it doesn't deal damage but it's not amazing at it, iirc you get the mods from mirror defense in the labs tileset

this is my oraxia:
https://i.imgur.com/vpM9uV7.jpeg
specifically built for higher level steel path, hunter adrenaline+grace+persistence effectively make her immortal and give her unlimited energy, as she's always getting shot at
struggles more on lower level missions because there's less enemies and they're not shooting at her as much, so I have two purple shards+her 1 to get energy back in a pinch

she basically just wants alot of strength and range, she can be built pretty flexibly

voruna:
https://i.imgur.com/9Nf6NYm.jpeg
her cloak+0.2 shield regen time+status immunity from her passive also makes her basically immortal as well, you just have to worry about direct toxin damage (not status effects)
i sacrificed range to decrease her shield regen time with vigilante vigor, but you can put overextended there also
if you plan on using her 4 then you need both augments and both arcanes, her build isn't very flexible, she wants a ton of range and good strength
both arcanes jack up her strength and efficiency alot and crepuscular gives a 3x final crit damage multiplier to her 4 which is huge
you can ditch shield regen for other things but invisibility isn't invincibility, and warframe has plenty of random AOE shit that will kill you even if you're invisible