According to the Evocations page on the wiki:
Anything which requires the evoke command (v) uses [Evocations], as does evoking (V) wands and using special abilities (a) granted by items.
Attacking units 2 squares away with a polearm like a spear or halberd is done by using e(v)oke. What exactly is affected by your Evocations skill when doing this kind of action?