I am only looking at the second shot when I say this, the first is spot on regarding the blend. You obviously know what you are doing and there is no guarantee I'd do a better job so don't take this the wrong way, just a case of having learnt the hard way how to try and make blends look seamless.
I'm assuming you shot bracketed exposures and blended them afterwards and this is not a physical grad line? If it is a physical grad line then always position it just below the horizon rather than above it or even 50/50 over it, the darkening of the sea with a hard grad line is less apparent than the lightening of the sky.
The way I would do it is as a combination of methods, probably using 3 exposures, but assuming only 2 try this.
First of all darkest one on top of brightest one, channel selection of brightest (blown) highlights from bright one, apply selection to a folder, put the darker exposure in the folder above the brightest exposure not in it. Add a black mask to the dark exposure now in folder and with a soft, reduced opacity brush literally paint through white where you want to recover the highlights in the sky. That will give you a recovered file, that may be still too bright in the whole sky area.
Then I'd flatten this down. I'd then create a selection of just the land, either using magic wand etc or colour channels. with the sea and sky being white but the land being black I'd then load another folder in the layers palette and apply this selection to it as a mask. Then within that folder I'd create levels adjustment mask and move mid point darker, (or a duplicate of your darker exposure if you prefer and change opacity of it). The real beauty of this technique is the fact that the land is protected with the mask on the folder, but the levels adjustment layer, or darker exposure within it, can have it's own mask so you can paint through or soft gradient the darker tones into the top of the image. I'd just paint a soft edged brush around the sea near the land knowing I didn't have to be accurate because the land won't be touched because of the folder mask. You can also feather either/both of the masks and tweak the opacity of the masks.
Also, you can create any other adjustment layer on the base layer (land) and locally edit that all at once i.e. sharpen just land but noise reduce sea/sky along with colour corrections.
If my typing rambling makes no sense and you are interested I can screen grab some examples of how this workflow appears if you wish.
