With this beginning the lance is used for its piercing ability. O sensei took off the blade for safety reasons but it is fundamental to keep in mind that the reality of this weapon is to pierce aite's body.
It is true that controlling uchi's right elbow is a condition to apply the technique properly. But, controlling the elbow is allowed precisely by the piercing. The control of the elbow is a only consequence of the tsuki.
If the piercing action "estoc" is transformed into an attempt to control the elbow as some kind of lock then failure is certain: not only uchi is not stabbed by the blade but the elbow control will be failed.
Please notice that it is important to to lay the end of the blade on your forearm. This allows to keep the blade firm, binding it to the body to convey a maximum of power and precision.
Understand the necessity of pushing on your extended back leg.
When the tsuki is done on uchi's left side, with the other end of the lance, (equally equipped with a blade in reality) your left wrist controls uchi's left elbow.
Aikido is not a sport, it is a martial art which laws (takemusu) are in harmony with the laws of the universe. Studying them allows the practitioner to understand his place in the universe. Aikido was born in Iwama, O sensei achieved in that village the synthesis of tai jutsu, aiki ken and aiki jo.
The International Takemusu Aikido Federation (ITAF) brings to the practitioner the structure he needs in order to work as close as possible to the reality O sensei MU defined. The official national representations are the guarantee of a teaching faithful to the Founder's.
In modern Aikido, weapons are hardly taught, if taught at all. In O sensei's Aikido, on the contrary, aiki ken, aiki jo and tai jutsu are unified and form together a riai, a family of harmonious techniques stemming from one unique principle. Each techniques helps understand all the others.
Peace is a balance between a human being and the world around him. The true martial art's goal is not to become stronger than one's opponent but to find in that opponent a way to realize harmony. There is no enemy anymore as such, but an opportunity offered to reach unified ki.