And kill Nshek!!!

But with KNIVES!!!

I disagree. You should start with X-Retsu to get the -50% heal of all sources. You have your Kaku to chase fleeing enemies, so you should save Kaiten for ignoring damage. If you hit and run, you should have no problem as well, because that burst of speed is enough to outrun your enemies, meaning you do not use his kit fully. Also, your X-Retsu gives you 3 ki stacks. Therefore engaging with X-Retsu is the best idea.

There is no point in getting a Clockwork as well, since you use auto attacks to deal the most damage, while using your skills to dodge skillshots or damage, and to escape. If you sell Tension Bow late game, i do not suggest it unless you are already decked out, then you can sell it for your final item.