>>96117722 (OP)As
>>96117754 says, use a long handle. Many were derived from farming impliments used to thrash corn - the long handle allowed the user to thrash the target repeatedly and quickly for less effort and without the jarring that a mace or club would cause with every blow to your wrist/arm. This is particularly useful when striking at targets from horseback when galloping through a crowd.
If you are worried about blocking and parrying, either carry a small shield in your other hand to parry with, or extend the shaft to pole arm length - you can parry with the pole (like a spear) or use the long reach to clobber them as they try to close with you.
They are good against those who try to parry a blow with a shield or weapon. When you swing at them, they raise the shield/weapon expecting the flial head to bounce off or entangle the chain, but instead you extend your reach on the swing to tap their weapon or the top/side of the shield with the staff and the head whips round to strike them.
Flails are also useful against targets wearing early plate, as most only had plate on the front of their bodies, with only mail and padding on their back - hit them with the staff and the head whips round to strike their less armoured parts.
You do need a bit of room to swing it though, so watch out for allies to the side and rear of you. It isnt a weapon for close formation fighting.
