Sword Art Online: Hollow Realization Cheats and Tips

If you have a save file from either the 'Hollow Fragment' or 'Lost Song' games select 'Check Transfer' at the 'Main' menu to unlock the corresponding bonus item.
Anneal Blade (Sword):
Save file from 'Hollow Fragment'.
Lost Song (Necklace):
Save file from 'Lost Song'.

Check out the video below to see a tutorial on how to unlock Dual Wield.
Watch the video

The following is a list of the promotional DLC outfits and how to get them. All the costumes unless noted otherwise are for female.
Livie Costume (God Eater colab):
Pre-order exclusive
Maid Outfit (Europe):
Bandai Namco VIP corner redeemable (free)
Maid Outfit (USA):
Pre-order exclusive
Navy Blue Swimwear:
Season Pass exclusive
Nightwear:
Pre-order exclusive
Soma Costume (Male) (God Eater colab):
Pre-order exclusive
Wedding Dress:
Season Pass exclusive
White Swimwear:
Season Pass exclusive