This word is read as "tou-ryu-ken". The top kanji means "climbing".
In the tradition of China, it was said that the carp that climbed up a waterfall will become a dragon. The waterfall was called "ryu-mon"(dragon gate). So, gateway to success is called tou-ryu-mon(climbing up the dragon gate).
This sword, "tou-ryu-ken" was named based on this proverb.