Ps 18 27You save the humble
but bring low those whose eyes are haughty.
  28You, O LORD , keep my lamp burning;
my God turns my darkness into light.
29With your help I can advance against a troop 
with my God I can scale a wall.

 Anytime the Psalmist mentions the attitudes like joy, praise, sorrow, and humility it is always holistic according to the law, covenants, curses, statutes , promises and decrees. In being humble we must the axioms so that we can understand self denial. Humility is not avoiding the truth of the bible in order to get along. All of these christian evidences of humility like turning our eyes off of self, thinking of others better than ourselves, understanding that we are the worse sinner and defending the most vulnerable is only accomplished through renewal. We must distinguish between destroying our gifts and hating hating in the context of renewal. The Psalmist is teaching that as he fights and wins the wars, he is displaying humility, by being faithful, blameless and pure in Gods work to destroy the corruption of these attitudes. God enables the Psalmist to destroy all of his enemies because God did the work in destroying the corruption in the attitudes giving the Psalmist the power to overcome the opposition of the nations. . 24The LORD has rewarded me according to my righteousness, according to the cleanness of my hands in his sight."my righteousness" -The Psalmist actions of fighting the war and winning. Then he says  25 To the faithful you show yourself faithful, to the blameless you show yourself blameless  26to the pure you show yourself pure,-God must destroy all the corruption in order for the Psalmist to be successful in war. The Psalmist wins the war because God renews his corrupted motives that generate the power when he fights.So humility is exercising power under control  Self denial is cursing the curse or pushing the destruction under our feet by controlled power. God controls the our power by His destroying grace.