surname recorded from 1248, and means "a spearman." This was a common type of Eng. surname, e.g.
Shakelance (1275),
Shakeshaft (1332).
Shake in the sense of "to brandish or flourish (a weapon)" is attested from late O.E.
Heo scæken on heore honden speren swiðe stronge."[Laymon, "Brut," c. 1205]
"Never a name in English nomenclature so simple or so certain in origin. It is exactly what it looks -- Shakespear." [Bardsley, "Dictionary of English and Welsh Surnames," 1901] Nevertheless, speculation flourishes.
[sheyk-speer] 
spɪər