When fighting her, attack three times, if it was blocked roll away once and 
start tapping Square.
If you do not hold any specific direction on the Analog-stick, just not 
touching it at all works. It
will automatically target Whiptail. You can dodge her small wave attacks and 
use your Speed
Stance to hack through the big waves to gain glyph ratings. If you do not 
press Circle to finish
her, she will never die. Just keep attacking and dodging; and hacking 
through waves to get an
easy three glyph rating.