For OP and everyone else that is struggling to find a sword bearer, just be brave and try it. I'm speaking from personal experience. We run hard Crota 3 times a week. The first two times, we have different sword bearers, but the third time they would switch to alts, leaving us without experienced sword bearers. I was the only hunter left and they convinced me to try it. It is harder than normal, but all you need to learn the timing. Here are the most important things to know.

1. Don't give up or get too nervous.
2. Use arc class and use the stealth abilities. Make sure you use the ones that let you go into stealth mode when you crouch, melee, and the one that doubles the length.
3. DON'T SHOOT ANYTHING. If you don't shoot anything, the thralls ignore you and the boomers hardly shoot at you.
4. After you pick up the sword and go to the rock on the left or right, tell your team to start shooting as soon as you go into stealth mode. This way you'll be on the center platform when Crota's shield is gone and no time is wasted getting to him. 4.5 Make sure a titan puts a bubble up on somewhere where the boomers will shoot him, do this as soon as the sword is picked up. They will focus on the bubble if the person inside is shooting at them.
5. As soon as the third strike hits, press triangle to drop the sword and aim AT HIS BODY to melee. This way you won't risk missing his legs. Also, make sure you hold the left analog stick forward when swinging the sword to speed up the animation.
6. After the second 3 smashes, jump away QUICKLY and sword glide away. Repeat this two more times and you'll kill Crota on the third sword.

You don't have to be a hunter to kill Crota, but if you have more than one in your raid team and need multiple clears, it makes it easier if you split up the responsibility. You guys just need to be patient when learning and you'll get it. I took him down on my fourth try. Good luck!