Singing skill and Wind skill function the same way as far as helping with buff potency and debuff accuracy, except that Singing skill also affects songs cast with a String instrument or "sung" without an instrument equipped, whereas Wind skill only affects those songs cast with a Wind instrument. Furthermore, for the potency of the buffs (most notably Marches), the tiers work by combining the Singing skill and the particular instrument skill.
Lady Jinte wrote:
Vlorsutes' Negotiation Skill rises 0.2 points
Vlorsutes' Observant Parent Skill rises 0.3 points
Vlorsutes' Argument Diffusing Skill rises 0.1 points