One comes across a total of four verbal forms of the so-called waw consecutive with the imperfect (wy$kb, wyhk, w'qtl, w'$m) in this brief textual remnant. While this narrative verbal form is usual in the biblical Hebrew, the Moabite of the Mesha Stone and in the prophetic text of Deir Alla, it is found neither in Phoenician nor in Aramaic. The only exception to this is the Aramaic inscription of Zakur, where one finds three examples of the imperfect with waw consecutive, a fact probably due to the probable Canaanite origin of the character (as shown by the vocalization of his name, documented in an Assyrian text). That which needs to be underlined is that the forms in question are not used systematically in the text of the Zakur inscription, but are only found in one passage of a strictly religious "flavour", in which the sovereign records his prayer to Baal Shamim and the divinity's response. The indiscriminant use of the waw consecutive in the Tel Dan inscription is thus a completely anomalous datum in the context of Aramaic epigraphy.
Garbini's observations on the use of the "waw consecutive" call for several comments; the primary problem is his restriction on the use of the available evidence. He states roundly that except for biblical Hebrew, Moabite, and the Deir Alla dialect, the waw consecutive is not found in Phoenician or in Aramaic, except for the Zakur inscription. In other words, except in the texts most likely, on the basis of geography and historical contact, to furnish authentic parallels to the Tel Dan inscription, the waw consecutive is not found!
I have the following observations:
(1) The fact that the waw consecutive is not found in Phoenician is not relevant, since the Tel Dan inscription is not written in Phoenician.
(2) On the basis of dialect geography, Israelite Hebrew (Garbini's term "biblical Hebrew" suggests that the form is not found in epigraphic Hebrew, but it is), Moabite, and Deir Alla form a Sprachbund in which the waw consecutive (better: narrative preterite) is still in use. Tel Dan's location would place it within the area of this isogloss. As the epigraphic attestation of what we might call Southern Old Aramaic mounts up, its partial similarities to Hebrew become more evident. The presence of the waw consecutive is what would be expected on the basis of dialect geography.
(3) Garbini states that the waw consecutive is not used systematically in the Zakur stele, but simply in one passage of strictly religious flavor. In Tel Dan, on the other hand, the waw consecutive is used indiscriminately, and this is completely "anomalous." It is unique; I think the word "anomalous" prejudges the issue. I am not sure that the 13 fragmentary lines of Tel Dan give us enough context to understand its verbal system; I'm not even sure that the 47 lines (somewhat less fragmentary) of Zakur give us enough to understand its verbal system. This is certainly all the more true for Garbini, who was writing when only the first fragment of the Tel Dan stele had been found. We just don't have enough information to say that Tel Dan is anomalous. (In fact, based on our current state of knowledge, it could be said that it is the Zakur stele's strange mixture of forms that is anomalous.)
(4) Garbini, as can be seen, tends to overstate the reliability of our dialectal knowledge, and he assumes airtight boundaries between dialects. This flies in the face of our current understanding of the West Semitic languages of the Iron Age as forming a dialect continuum.
(5) It should be noted that Qumran Aramaic still has a few examples of the waw consecutive. Therefore it is not quite true that its use in the Tel Dan stele is "completely" anomalous.
(6) As Takamitsu Muraoka has observed, consideration of the "waw consecutive" in Tel Dan is connected with the use of the preterite form without waw (occurs twice). This gives a remarkably archaic look to the verbal system, reminding us, as Garbini rightly says, of Ugaritic. I can't comment on what Garbini says about the preterite form (which he objects to) because the crucial paragraph (which follows the one quoted above) is truncated in the translation, and I can't tell exactly what his point is. Is the use of the preterite surprising? Yes. But there are examples of the preterite without waw still surviving in the Hebrew Bible (in its oldest strata) and it is not unexpected that there should be some epigraphic attestation of this usage in a newly-discovered Northwest Semitic text from the 9th century BCE.
BIBLIOGRAPHY: The verbs of the Tel Dan stele have been widely discussed. See, inter alia, Muraoka, T. (1995). "The Tel Dan inscription and Aramaic/Hebrew Tenses," Abr-Nahrain, 33, pp. 113-115; Muraoka, T. (1995). "Linguistic notes on the Aramaic inscription from Tel Dan," Israel Exploration Journal, 45, pp. 19-21; Muraoka, T. (1998). "Again on the Tel Dan inscription and the Northwest Semitic verb tenses," Zeitschrift für Althebraistik, 11. See also: Victor Sasson, (1997). "Some Observations on the Use and the Original Purpose of the Waw Consecutive in Old Aramaic and Biblical Hebrew," VT 47, 111–127.