Aikiken is a sword practice that has a clear relation to empty-handed Aikido techniques. It is practised with the wooden bokken.
Aikiken was canonised by Morihiro Saito, who developed its forms from the teachings of O-Sensei. Aikiken was strongly influenced by the sword school Kashima Shintō-ryu, but it must not be mistaken for it. Kashima goes beyond Aikido forms and has a different focus (duelling character). Sword practice in Aikido dojos is often influenced by other styles, too, such as iaido.
Working with weapons is very important for the improvement of Aikido practice: it creates a deeper understanding of posture, forms, distance, timing, awareness and presence, and it magnifies (technical) inadequacies which are not as visible in empty-handed Aikido techniques.
The wooden sword (bokken) is always treated as if it were a sharp weapon.