Hello,
I am not sure if you have already resolved this problem but I thought I would respond anyways! I have two Isul dolls and find that their joints are often a little stiff. However, to me they feel more sturdy and arguably less fragile than the Pullip or Dal models. Try to gently bend the hands or rotate them. You may find they are just a little stiff. I often fear that I will damage my dolls joints and this was especially the case when I first bought them. Once you get more familiar with the joints and how they move you will feel more comfortable posing them. Also, I have an Isul Lir and would advise you to be cautious with the coat and sash. I find that the gold buttons seem to come off the coat frequently (even though I just use him for display purposes) and the little charms on the sash break easily. For Isuls I also recommend only bending the knees as far as a Pullip's knee would bend. Isul knees bend farther, but it appears to stretch the plastic and I don't know if this has potential to create a split in the leg piece. Good luck with your Isul Lir! ^_^