I can confirm it's Weakness.
Took my N/Mo 55 out to the Isle of the Nameless, stood next to the Student of Weakness and... Smiting, Healing and Prot all had red numbers next to them on the K screen, Death stood at 0 (no rune or attrinute points, white number), and Curse, SR and Blood were Blue numbers, yet still bore the 'Your rank in XXX is normally...' message.
Seems to me
1)Attributes at 0 stay at 0
2) Attributes boosted naturally, without a rune applied, go red.
3Attributes boosted, with a rune, stay blue.
Sorted
