Rashi: I will shield it like a wall of fire around it.

Radak (8-9): People will dwell confidently outside the wall, without fear of people. No person will be able to touch you to harm you, just like one cannot touch fire, lest it burn him.

Malbim: I will be the city guardian, like a wall that people fear to approach, for a fire outside consumes anyone who touches them.

Rashi: My Shechinah will dwell for your honor.

Radak: Honor will hover over them ? "u'Vara Hashem Al Kol Mechon Har Tziyon" (Yeshayah 4:5).

Malbim: In the big world, whatever is more important, it surrounds [the less important] and guards it; the physical world is surrounded via all worlds (the spiritual worlds are more important). In the small world, i.e. man, what is more important is internal; the heart is surrounded via all limbs. I explained in Yechezkel "v'Hayah Mishkani Aleihem?; bi'Hyos Mikdashi b'Socham" (37:27-28) that the primary Mikdash will be on them. It will surround them, like in the big world, and they will be the Merkavah for the Shechinah. The Mikdash will be amidst them only so the Goyim will know ? "v'Yad'u ha'Goyim Ki Ani Hashem Mekadesh Es Yisrael bi'Hyos Mikdashi b'Socham" (ibid.) Our verse teaches that I will be amidst them only to increase Yisrael's honor; really, the surrounding light is greater than the inner light, just the inner light is recognized more.