But there is something strange about the usage of the verb φρουρεω. The following citations are YLT of the Hebrew and in each LXX instance the Greek translation has a nominal form of our verb, which suggests that in such contexts in the Judeo-christian Greek tradition word indicates a body of soldiers in control of a situation, here garrisoning a city.
2 Samuel 8:6 and David putteth garrisons in Aram of Damascus, and Aram is to David for a servant, bearing a present; and Jehovah saveth David whithersoever he hath gone;
2 Samuel 8:14 and he putteth in Edom garrisons—in all Edom he hath put garrisons, and all Edom are servants to David; and Jehovah saveth David whithersoever he hath gone.
1 Chronicles 18:6 and David putteth garrisons in Aram of Damascus, and the Aramaeans are to David for servants, bearing a present, and Jehovah giveth salvation to David whithersoever he hath gone.
1 Chronicles 18:13 and he putteth in Edom garrisons, and all the Edomites are servants to David; and Jehovah saveth David whithersoever he hath gone.
The translation of φρουρεω (from the LXX) to "putteth garrisons" was done by a modern translator and therefore is not evidence, even if, in these cases, the translation makes sense.
Furthermore, why mention someone, through a garrison, had to have complete control of a city, just in order to arrest only one individual? That's an overkill which does not fit.
However, 'In Damascus the ethnarch of Aretas the king
put/kept/set/placed some hired men in the city of the Damascenes, wishing to seize me,'
OR 'In Damascus the ethnarch of Aretas the king
guarded with some hired men the city of the Damascenes, wishing to seize me,'
makes more sense.
Cordially, Bernard