Pieter's sword was not the ideal tool for cutting through the thorns, but it sufficed. Emerging rather more scratched and bedraggled than before, Pieter led the whinnying horse out with him.
As soon as it had left the thicket, it darted towards the trees. Pieter had a hold on its reins; digging in his heels, he and the horse danced in a clumsy circle around each other. The villager's body finally slid from the horse's back, dropping gracelessly to the ground. Nostrils flaring and eyes flashing in wild and unreasoning fear, the animal twisted and pulled at the end of the reins...
You can test Strength to simply try to hold the horse in place until it gives up; alternatively, you can test Animal Care (since it's a Basic skill) to try to calm it down.