@Hillan Bogard does not manipulate blood. Its to Op'ed
I mean... arguably, that's exactly the sort of thing that
should be viable with the Aka-Aka no Mi, at least against weaker opponents. The wielder has to be able to see red to use the fruit's effects, so Bogard can't just puppeteer whoever he likes, on account of most people not having red-coloured skin... or no skin, or transparent skin, or some other situation that shows off a great deal of the muscles and blood and other red stuff that lies in the body. In theory, then, the best he could do (and even this is a maybe as far as I can see, but anime logic, so it'd probably work) is effectively "pull" the blood out of a target's body through any open wounds they have to make it flow faster, thus desanguinating them more quickly than would otherwise occur, and then of course weaponising the mass of blood as he sees fit.
Also, unlike the setting of, say, Avatar: The Legend of Aang, blood manipulation has its counters here - a stronger-willed being might be better able to retain or otherwise command their own blood through sheer desire to not die horribly and/or Haki recolouration, whilst a Life Return user could use their enhanced body control to resist it, or perhaps just heal the offending injury instantly if they're skilled enough. And of course, it won't work so well against those who've done something that pre-empts the existence of red blood in the first place, i.e. many Devil Fruit users - specifically Logia users, perhaps some Paramecia users who lack blood in a transformed state, and Zoan fruit users whose creature has non-red blood, e.g. lobsters with blue blood. Also, while it's not that important since Bogard can't go in the ocean anyway, large quantities of human blood actually turn large masses of water yellow due to the plasma content, whilst below a certain depth, the inability of longer light wavelengths to penetrate down that far means red colours are impossible, so human blood turns green beyond that point.
And
that all assumes Bogard manages to injure them in the first place... there's a lot suggesting that blood manipulation by the Aka-Aka no Mi isn't really as dangerous as it seems in this setting given the fruit's limitations, is what I'm saying. If the fruit's power was just sheer manipulation of blood without the Aka-Aka no Mi's restriction on sight only, then it'd obviously be problematic.
