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 Saitō, who developed its forms from the teachings of O-Sensei.
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.