Some consistent ways of getting this "corner wcs" in the edge of the water in blue lake without needing a 1f nail slash right before touching the water:
Do the classic nail + inv setup a bit above the water (inv 1f after the slash)(clip 1)
Sliding down the wall while slashing will give you wcs is you are still in the nail animation and holding towards the water when you enter it. The main problem with this is that it requires a 1f left release, which can be tricky. To fix this, we can hold analog right as well as digital left, which will make us start going right as soon as we enter the water (clip 2). The only problem with this is that if we hold l+r for 3f or longer before the slash ends (or before we touch the water in our case), the knight will get pushed out of the wall (clip 3), which messes up the wcs setup. To perform the wcs setup properly (clip 4), we therefore need to:
Cling to the wall and keep holding digital left
Slash low enough so it doesnt end before we touch the water
Start holding analog right 0-2f before touching the water
Ladies, gentlemen and everything in between, here we have 0 slash (1st vid regular dash setup and 2nd is dm setup)
Turns out that dashing first thing in the room gives you perfect subpixels for corner wcs. In addition, neither downdashing nor dashing off of these 2 walls (image).
There's been debate over whether using analog left or digital left is better for 1 slash, and there are cases for both.
Using analog left increases your max fallspeed, meaning the window to clear the ledge is tighter, but if you do clip the ledge, since you'll continue walking right you can sometimes keep the WCS anyway.
Using digital left increases this window, but I've also noticed it tends to turn you to the left when you enter the water if you continue holding it, which can also eat your jump for some reason, so you either have to eat this timeloss or stop holding the WCS before entering the water.
Switching between digital and analog, as shown in the clip, should give you the best of both worlds. You get some reduced fallspeed on the first dash by holding digital left, then switch to analog in case you clip the ledge and so you don't turn when entering the water.
Backup wallcling storage setup for blue lake. Can potentially be faster than 1 slash by as much as .4 if you minihop instead of fulljumping, but it's pretty inconsistent then.