One of the biggest cons is that above the tv is way too high for most people's optimal/comfortable viewing. There are several different opinions about the best height at which to view a tv, but generally when sitting you should be staring at the center of the screen or at the very highest at the bottom of the tv. Unless you have an unusually low-profile fireplace, watch tv standing or are like 6' 6" tall, a tv mounted above the fireplace is going to make for some uncomfortable viewing.

If they are accent chairs, put them right next to FP! Pull them away when you have fire.

Try the TV where the sofa is now and float the sofa perpendicular to the fireplace where you currently have the big chair. Perhaps the big chair can then go where the TV was for a quiet spot for one. Or even better, pull the loveseat off the wall and put the big chair to its left flanking the fireplace.

You could really use anything - I do support the no fire arms idea. Look at your hobbies e.g if you are into sailing maybe some Oars, cycling a brightly covered wheel rim, gardening an antique tool, antiques & collectables a brass beg warmer, music a gitar, violin or saxophone, or fishing rods etc if all else fails a massive traditional or highly decorative modern mirror which will throw the light around the room. Make it something that shows who you are & your personality. It must be a passion or somthing rhat brings you pleasure.