GARBA is a name element of its own right. The Germanic word *garba or *garva means "ready (for battle)". Names with the full element *garba are extremely rare. Usually it is shortened to GARU, GARO or GARI as a first element (Garufrid, Garoman, Garimar), the U, O and I being a linking vowel. As a second element *garba usually shrinks to -gar (Baldegar, Irmingar, Ortgar …). A lot of times this causes confusion with the element GER (gair), "spear, lance". Sometimes it is also found as -car and then could get confused with HARJA > HER like in
Herbert.
So the famous Italian liberator (if this is the correct word) Guiseppe Garibaldi could derive the second part of his surname either from "ready" or "spear".
This is taken from:
Ernst Förstemann: Altdeutsche Personennamen (1906)
Henning Kaufmann: Altdeutsche Personennamen, Ergänzungsband (1968)