That is the vent for a direct vent fireplace I believe. It can not be altered or covered in any way. As far as the sharp corners on it the upper portion that is a rain deflector, the edges can trimmed round slightly and the burrs that may be left can be sanded smooth.

Now I don't want to alarm you, however I see a patio chair near it that is too close to it. While sitting at the table I noticed a strange glow through the patio doors. I went outside to see what the heck it was and a patio chair had been blown against the vent and caught fire. The foam cushion was ablaze and black smoke was billowing from it. Thank goodness I was home, the deck and the house may have caught fire.

They can get very not, if you have small children take care they don't touch it even when the fireplace isn't on the pilot alone makes it very warm and it is hot when the unit is on.

Never touch it and move anything flammable away from that thing. I know it's a pain but that's what we have to live with a direct vent. Not much thought about placement of the unit is considered when installing. I may be anal about this but it is a safety concern where flammable objects may be concerned and small children. Had a insurance loss prevention officer out on his regular inspection and I asked him about the location of ours and he said it was fine, I told him the story and he was dumbfounded. Never thought about it before.

Please don't alter that thing other than maybe trim the edges on the rain shield.