Well, I'v never played this outside of hardcoe mode, and i'v also never used her before. This is my first time coming across her. Since I am not using any "essential" mods, I am wondering just how useful she will be. Mainly asking because she is melee, and I watched a deathclaw kill me in two hits.... so yaa...

Well, a Deathclaw will likely kill her pretty quickly too, if you're low level and don't upgrade her equipment and set her on melee.

Upgrade her armor, give her Pushy and a decent energy weapon and ammo for ranged attacks and she's deadly, especially once she's gotten her perk for completing I Could Make You Care. On melee, she'll make short work of just about any enemy in the game short of Deathclaws and such.

Beware of Cazadors, though - she suffers from the companion poison bug like they all do, though there are mods that will fix that.

One of the worse companions, unless if you give her a good armor like a T-51 brotherhood(find a couple in dead bodies in the Repconn HQ, give her a minigun or laser pac with a lot of ammo and tell her to use gun. Melee going against creatures like Deathclaws and Cazadores in hardcoe she won't stand a chance. Usually when I see a deathclaw I tell her to wait back and engage trying to cripple them while she is in the back and bullets are flying. It works most the time.

Luckily I found that armor before I read this or it would of been a major spoiler for me. As of now she does fine with melee having the Power Armor. Now if only she would actually WAIT when I Said wait... and not instantly run out, setting off traps which kill me and ED-E...

Besides I Could Make You Care, don't forget about Elijah's Last Words

I guess in that case you can tell her to wait outside before entering a building. In this glitch game often companions run around like crazy setting traps or appear in the middle of the map, or even run after an invisible enemy then stops and comes back.

It's not common knowledge, because she doesn't tell you, but Veronica is just as good with Energy Weapons as she is with Unarmed.
She can punch a deathclaw to death pretty fast (if she doesn't die first), but she can also snipe them with the Gauss Rifle with scary accuracy at medium to high levels
She is like the Energy Weapons version of Boone. She just doesn't tell you that.