I went to battledome for a fight.
I follow the instruction there until I got to the battle page.
From the yellow arrow blinking at the bottom-left I suppose I must choose a weapon by clicking the square there, but nothing happen. I couldn't choose a weapon. When my mouse hover there it become the unclickable cursor (the black circle with a cross like a stop sign). What should I do?

It's a common glitch, even before this started. Refreshing the page a few times often does the trick :)

 

If you have a faerie ability, clicking that first also unlocks being able to choose a weapon too.

Nope. Doesn't work. I guess I will have to withdraw, learn faerie ability then try again. I am so reluctant to do that. *sigh*

This is a glitch as the Battledome is still in Beta and happens when the opponent hasn't said his first words such as "Let's Fight!"

 

You can refresh or wait until the opponent says his first words... it will then let you select your weapons.

I'm pretty sure if you keep refreshing, it will allow the battle to begin, and not count as a withdraw (lose).

You can also go to any other page on the site. Then, go back to the battledome and click the "BATTLE!" button.

Sometimes you have to wait for the combat log to load, too. I've been getting that a lot. Just let the page sit for a minute and click back to it.

What I do when this happens is click on the circle-arrow or double >> (normally used to skip battle or repeat the scene). This unlocks the blocked mouse for me.