What does the symbol with a shield and two swords next to clan members' names mean?

This symbol means that those player can participate in clan's war, The other players who don't have it are spectators and they can't participate in war.

The logic behind that is like this :

• If a player join your clan after you started the war they will become a spectator and will not be able to actively participate in the clan war.
• If your clan members are more than enemy's clan, The players who have lowest trophies will become spectator so both clans have the same number of members ( e.g 30 vs 30 or 45 vs 45)

Also there's another icon you can have besides the bronze shield with crossed swords. You can have a dull silver or grey shield with crossed swords and a red line or bar underneath it. This mean you are ineligible to participate in a clan war for a period of time. I was in a clan and I started a war then left my clan for another clan. I have to wait until my old clan finishes the war that I abandoned before I can participate in another war. If you click on the "i" icon next to your blue level in the top left hand corner it will show your player profile. On the top left it will show the bronze shield with two crossed swords symbol for coc clan wars and say how many days or hours left until uou are eligible to participate in a clan war again.