In her time as leader of the Order of Mata Nui, Toa Helryx had needed to make difficult decisions, something she had always known. She had sent agents on missions she knew they might well not come back from. She ordered the deaths of everyone who knew the location of Artakha.
Helryx spent many thousands of years honing her control over water to perfection.
Helryx's mind was well-shielded against mental attack.
Helryx's weapons were made of protosteel.
Helryx was never a Matoran.