Note: There is another denarius of Hadrian, RIC II 301, which shows a personification of Asia carrying a similar "hook". Curtis Clay collated various authorities' notes on these "hooks" on the Forum Classical Numismatics Discussion Board on 12 March 2009:

"As far as I can see, no solid evidence exists for the identification of this "hook", so the best conclusion would have to be that we don't know what it represents.

Strack, Hadrian (1933), does not discuss the hook held by Hadrian's standing or seated Annona, and admits his ignorance by calling it "?" in his descriptions of the types, nos. 165-6. Asia's attribute he calls an acrostolium, no. 299, following Cohen, but without any discussion in his text.

Mattingly, BMC III (1936): Annona holds a pruning-hook, the sign "of culture of plants and perhaps particularly of the vine" (p. cxxxv). Asia holds "acrostolium (or hook)", without further discussion (p. cxliii).

Toynbee, Hadrianic School (1934), p. 50: Asia holds a pruning hook, which refers to viniculture in Asia, the same attribute that Annona holds in the two earlier types of Hadrian.

J.C. Balty, Asia II, Lex. Iconogr. Myth. Class. II.1 (1984), p. 859: despite Toynbee's argument, the identification of Asia's attribute as a pruning hook with reference to the province's wine production is uncertain.

H. Pavis d'Escurac, Annona, LIMC I.1 (1981): no mention of Hadrian's two types with the uncertain attribute!."