Onkelos the Convert is said by the Talmud to be the author of the official aramaic translation of the Pentateuch. Rashi and Maimonides understand Onkelos as having a tendency to interpret physical reference to God metaphorically. Indeed it seems very evident that throughout his work, Onkelos adopts this stance in his translation.
However I was looking in Deuteronomy 26 and I saw that in verse 8 (Hebrew (Masoretic)-Aramaic (Onkelos)-English (OJPS)):
וַיּוֹצִאֵנוּ יְהוָה, מִמִּצְרַיִם, בְּיָד חֲזָקָה וּבִזְרֹעַ נְטוּיָה, וּבְמֹרָא גָּדֹל--וּבְאֹתוֹת, וּבְמֹפְתִים.
ואפקנא ה', ממצריים, ביד תקיפא ובדרע מרמם, ובחזוונא רבא--ובאתין, ובמופתין.
And the LORD brought us forth out of Egypt with a mighty hand, and with an outstretched arm, and with great terribleness, and with signs, and with wonders.
Onkelos translates hand and arm simply. He also does this in Exodus 13:14, And Deuteronomy 6:20, regarding hand. This is all in the context of the exodus, so their is a commonality as far as context. Why does he not use metaphor in this area? The only other use of arm that I am aware of in the Pentateuch is Deuteronomy 4:34, where it is translated the same way, in the same context. For hand, see Exodus 9:3, and 7:4, where Onkelos interprets hand to mean plague or strike.