There are 3 chests behind the locked door here. One item is of particular interest.
There are images waiting for you in front of the middle chest and mummies in front of the other two. Fortunately they are easy to avoid. You may want to fight them for experience. Watch out, images can stun you and mummies can put you to sleep. They shouldn't be any problem if you're packing FIR2 or HRM2.
Here's the reason you came here. The Power Staff is worth 12345G, so you can sell it for 6172. If you spent some time at Finger Point you probably aren't in much need of money, and the Power Staff is the most powerful Black Mage weapon for quite a while. It does have poor hit%, but you never really rely on the BM to fight do you?
Just look at it, it's green! That's the reason I use it.
The falchon is probably the best weapon you have for a Thief, but not for long.
Put this on a fighter. You'll find a better one of these soon too.