לְדָוִד: בָּרוּךְ יְהוָה, צוּרִי-- הַמְלַמֵּד יָדַי לַקְרָב; אֶצְבְּעוֹתַי, לַמִּלְחָמָה. -Mechon-Mamre
My free translation:
By David: Blessed is Hashem Tzuri, he who teaches my hands in battle, my fingers in war. (emphasis mine)
Why does David mention his fingers?
I have thus-far only checked the Soncino Tehillim, whose brief note adds little understanding to the passuk.