I have a pc who has a scoripin tail and want the collective opinion, should the tail be free movining like a arm or leg with the poison barb being at the tip or should it be just like a scoripin tail requirering the pc to duck or crouch to strike with it?

which god are they aligned to?

currently unaligned but i roled a 4 sided dice to determane which tail and the pc got khorn

Unaligned characters do not receive any of the specific god variants of the gift.

What Bogi said, if they are unaligned to a God then it's just a generic tail which allows them an extra standard attack. Consider it like an oversized dino or reptile tail or something. Can't think of many other tail like things which would have enough clout otherwise! They should only get the other versions with their bonuses if they are aligned to a god. However what's done is done and while the rules say one thing, you as GM can say another. Maybe Khorne has his eye on them despite them not being fully aligned!

So to the question at hand, generally for a scorpion like tail, from watching how they attack it tends to come up and over their torso and I dont believe they can move it side to side that much. So it would need to come up and over. Whether they need to duck probably depends on the length of the appendage, what you're hitting and where as well as the size of the character. If you have given them a long enough tail it may be able to reach up their back and over the head to strike the prey. I would probably argue that based on the description of the tails use (an extra attack) that a duck action would require them to perhaps sacrifice some action in order to use it thereby mostly negating the extra limb so probably to answer your question:

"No, I would not say they needed to duck based on the description of the gift".

You should reread the Gifts of the Gods section. You're obviously doing it wrong. The unaligned tail is in the description. Only aligned get aligned bonuses.

You should reread the Gifts of the Gods section. You're obviously doing it wrong. The unaligned tail is in the description. Only aligned get aligned bonuses.

..or just possibly he did read it, and decided to deviate from RAW.

Anyway, this isn't at all helpful with the original question:

I have a pc who has a scoripin tail and want the collective opinion, should the tail be free movining like a arm or leg with the poison barb being at the tip or should it be just like a scoripin tail requirering the pc to duck or crouch to strike with it?

If the character actually did get a scorpion tail, I'd probably give him/her exactly that. One that arcs high enough into the air that s/he could attack someone to the front with only minor trouble, but which would be hell to hide.

alright thanks i may of missed that in the gift of gods so i will reread that, the character can still be changed due to not being into play for the first time. im new to GMing and the character is mine so i do expect to miss or forget a lot of rules and stuff

Meh the rules are there to guide you, having an interesting story and characters is always more important.

Use what works for your games and change the rest as you see fit, it's all about having fun at the end of the day.

Make it count like an extra arm! (that can't hold anything ofc).. And then let your player describe how it looks and works in apperance, but just let it count as an attack, or an extra attack he can.