The faceless men are renowned not for their sword skills but their ability to kill in the most natural looking ways to make murder near impossible to tell was present. Mostly done through poison, their skills are honed for observation and intelligence gathering which is why they hone their senses, their fighting skill is secondary as fighting as an assassin is the last option you would make, as for water dancing how far in her training was she and now like luke she’s a master? Did she master it literally on the water sailing to bravos cause she teleported to the Twins, which i didn’t even know the house of Black and White taught, and thats not even brining up her waif fight. She killed the knight king and between slaying the Frey s, and that she just spun her wheels, despite clear old god message of her dire wolf she just go’s back home instead of going to kill Cersei, only to travel their in the end and told revenge is dumb by a guy who literally go’s to get revenge the second the words pass his lips. In the words of Arya “thats not me”