Olive oil was used also for medicinal purposes. It was applied to the sick, and also to wounds to soften them (Isaiah 1:6).
The expression, "anoint the shield" (Isaiah 21:5), refers to the custom of rubbing oil on the leather of the shield so as to make it supple and fit for use in war.
Hospitality
It was the custom of the Jews in like manner to anoint themselves with oil, as a means of refreshing or invigorating their bodies (2 Samuel 14:2; Psalms 104:15, etc.). The Hellenes had similar customs. This custom is continued among the Arabs to the present day. Since about 3,000 years ago, Persian Zoroastrians honor their guests with rose extract (Golab), while holding a mirror in front of their guest's face. The guest holds his/her palm, collects the rose water and then spreads the perfumed liquid onto their face and sometimes head. The words of "Rooj kori aka" (have a nice day) might be said as well.