Woe to us! is a repetition of the same lament found in the previous verse and should probably be translated in the same way unless it is stylistically unacceptable to do so.
The power is literally “the hand.” The Hebrew word for “hand” is frequently used metaphorically in 1 and 2 Samuel and throughout the Old Testament to mean “power” or “control” (it occurs, for example, in 7.3, 8, 13, 14; 9.16; 10.18; 12.9; 14.37; 17.37; 2 Kgs 13.5).
These are the gods … in the wilderness: the reference is to the account in Exo 7–12. The plagues actually struck the Egyptians in Egypt before the Israelites began their wilderness journey. For this reason some change the Hebrew noun in the wilderness to read “and with pestilence.” Compare New American Bible: “that struck the Egyptians with various plagues and with pestilence.” It is recommended that translators follow the Masoretic Text. The word wilderness may present significant problems to translators who live in parts of the world where there simply are no regions that are dry and sparsely vegetated. But the most important characteristic about wilderness areas is their remoteness and the fact that people do not normally live there. It is a region that is uninhabited and virtually uninhabitable. Most translators will have already dealt with this problem in translating the New Testament and may refer to solutions found there.
Gods: the people of the nations around Israel worshiped numerous gods. Perhaps the Philistines thought that the Israelites also had more than one god. However, it is possible, and perhaps better, to render the nouns, adjectives, and verb as singular here (see the comments on verse 7). Revised English Bible says “Who can deliver us from the power of this mighty god?” New Jewish Publication Society’s Tanakh also renders these words as singular but capitalizes “God” as referring to the God of Israel: “Who will save us from the power of this mighty God? He is the same God who struck the Egyptians….”
Plague: the Hebrew term so translated here is elsewhere rendered “slaughter” (verse 10 below as well as 6.19, and Josh 10.10). But the term is used in a general sense here of “disasters” (New Century Version). Traduction œcuménique de la Bible speaks of “all sorts of blows,” and Contemporary English Version refers to “all those horrible things” that happened to the Egyptians.
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on the First and Second Books of Samuel, Volume 1. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here .