Blessed be the Lord my strength - Margin, as in Hebrew, “my rock.” See the notes at Psalms 18:46, where the same expression occurs in the Hebrew.
Which teacheth my hands to war - Hebrew, “To the war.” See the notes at Psalms 18:34. The Hebrew is not precisely alike, but the sense is the same.
And my fingers to fight - Hebrew, my fingers to the fight. That is, he teaches my fingers so that I can skillfully use them in battle. Probably the immediate reference here is to the use of the bow - placing the arrow, and drawing the string.