Pre-buffs, pretty bad. Post-buffs, pretty excellent (she just got her last one this Halloween). Yes, she's primarily a Quick DPS, so Skadi = Good, and Double Skadi = Slam Dunk. Just complete those buff quests/interludes.

Servants:
Skadi
MHXA
Waver
Ganesha
Osakabehime
Atilla Santa
Santa Nightingale Calamity Jane Chiron
Tristan
Hans
Kojirou / Fuuma / Cursed-Arm / Jing Ke

CE's:
Traces of Christmas
Three Anglers
Can't Fight On An Empty Stomach
Merry Sheep
CKT
Cute Orangette
Moment of Tranquility
Midsummer Moment
Black Grail
Kaleidoscope

Codes:
Star Severing Sacred Sword
Balance Scale Of The Universe
The One Bearing Fortune
Armament Of Victory
Dragon Of Twilight
Dragon Slayer
Merlin
Crest Of Humanity
Aurora Borealis