Itosu was the creator of  the third Tekki kata, Tekki Sandan,  

Tekki Sandan contains some of the techniques already seen in the previous two Tekki Kata, but with some alternatives as to how to perform them.   
For example the sweeping blocks and close punches of the first two Tekki are repeated but done differently.

. It also contains techniques from Jion, Jiin, and Heian Sandan.

Tekki Sandan is considered to be an advanced Kata and is not seen on the grading syllabus until 3rd Dan. This is probably due to the opening sequence of nine moves, repeated later in the Kata, seen above.
To perform this sequence properly with strength, Kime, speed, direction, breath control and muscle tension / relaxation at the critical points of each technique, is not something you will often see from a Karateka with only few years experience