"Horn" is a symbol of the power, authority, dominion of the Will of God as expressed in His Laws, Covenants, Commandments.   "Horn of Salvation" is the Will of God, His Commandments, revealed by Jehovah God to man, by their fulfillment gaining power to save him from various errors, deliver him from sin and its consequences. "Horn" is also a symbol of spiritual power and authority, which acquires a righteous person - a person who fulfills the Will of God, His Commandments.
Negative Meaning.  

"Horn" is a symbol of power and authority, manifested by people living in disobedience to the Will of God, in opposition to His commandments.

"Horns of the wicked" are the dominant ideological, political, religious models of arrangement of sinful society and their ruling spokesmen, founding various false ideologies, dogmas, false doctrines, to which the peoples serve and obey. 

"Horns of the wicked" are also various methods of manifestation by leaders, rulers of pride, stubbornness, arrogance, false confidence in their rightness, based on a variety of political, religious, psychological, ideological, economic, physical violence against man.

"Horns of the Altar" is the imaginary power, arrogance, self-righteousness, reliance in the religious fanaticism of people who self-righteously identify themselves with the true Faith, but who by their perversion and disobedience to the Will of God, have apostatized from it.

"The Horn of Moab" is a symbol of the religious, physical, psychological certain strength, power, influence of the secular rulers of the nations.