Depending on the inside of the horse's mouth (the interior / internal conformation), the horse may not be able to handle a jointed snaffle bit. The Icelandic Horse tends to have a low palate. Having heavy contact on the jointed bit, with a noseband, can be very painful and devastating for the horse.

In video, you will see a lot of Icelandic Horses fighting the bit. They have not learned how to accept the bit, naturally. The bit may not be the right shape for their mouths, and the noseband may be too tight.

The horse in this image has an icelandic bit in his mouth, which is jointed, and shanked; a bit which is very severe. For it to be used with a noseband, is extremely questionable. A horseman, a good trainer, would not have the need to use a broken, shanked bit, with a noseband on a good horse.

Click onto the image, to see a larger version of the picture.