Contemporary usage of “awful” only has its origins some 200 years ago, in a slang form of finding both concrete and conceptual objects or persons monstrous or bad; be it the state of a nation, or the dramatising of an adjective, as per the letters of Keats. Colloquialised versions of the adverb followed shortly after, from Twain to Paine. This suggests a paradigm shift in the power of the word, perhaps introduced by the Victorian novel: a wilful playing down of the original meaning as something more natural, mundane and relevant to a speaker’s everyday life.
In the objective sense of the word, its etymology stems from the noun “awe” and, ironically, the striking of “a subjective emotion... fear... dread”. Stemming in turn from the Old Norse, and Old Germanic, the suffix “-ful” makes its Anglo-Saxon appearance as slang, from the time of Alfred the Great up through the 1800s. However, this use relates at first to vast “awefull armies” and scenes that inspire dread, such as plagues, and massacres: a sense of horror.It is the words of Ælfric, circa 1000, which attempt to evoke instead a sense of God’s greatness, but other writers choose to subvert this as an earthly reverence in men only. It isn’t until Tudor England’s power play between Reformation and Counter-reformation that the inspiration of reverence and respect re-emerges. Even then, this subjective sense of being “filled with awe” merely touches upon exaltations of God rather than settling there.
 Thomas Green Fessenden · Pills, poetical, political, and philosophical: prescribed for the purpose of purging the publick of piddling philosophers, of puny poetasters, of paltry politicians, and petty partisans · 1809. John Keats · Letters, 1814–1821 ed. H. E. Rollins 2 vols. 1958 Mark Twain · The adventures of Tom Sawyer · Authorized ed., 1876. Leipzig: Bernhard Tauchnitz Ralph Delahaye Paine · Comrades of the rolling ocean · 1923 "awe, n.1". OED Online. September 2011. Oxford University Press. http://www.oed.com/view/Entry/13911 (accessed November 01, 2011). King Alfred · Boethius' De Consol. Philosophy · 888 William Warner · Albions England: a continued historie · revised edition, 1602 (1 vol.). London: E. Bollifant for G. Potter Daniel Defoe · A journal of the plague year · 1st edition, 1722 (1 vol.). London: Printed for E. Nutt; J. Roberts; A. Dodd; and J. Graves John Richard Green · A short history of the English people · 1st edition, 1874 (1 vol.). Ælfric of Eynsham · Deut. · 1000
 "awful, adj.". OED Online. September 2011. Oxford University Press. http://www.oed.com/view/Entry/13943?redirectedFrom=awful (accessed November 01, 2011).