According to this, http://www.reddit.com/r/ffxiv/commen...d_foe_requiem/, Foe Requiem affects all spell damage, not just "elemental" damage. Also, they go on to state that it does NOT affect Windbite, Flaming Arrow, or other skills whose descriptions indicate elemental damage, but are not spells.

Can you confirm/deny whether or not this is true, and if it is true, change the Foe Requiem skill description (and probably the accompanying buff tooltip) to reflect the accurate information? Something like "Descreses resistance to spell damage by 10%", perhaps.