So he really can sense her even if she just has a little slime tentacle out. That's probably going to be an issue at some point.
Which is fine, the author is quietly telling us the strength thing only works in combination. It also probably means she can't coordinate using a slime part alone while strengthening the human part with slime. Or at least she's not used to it. This author doesn't really outright tell us a lot of things, that's reserved for humor, but drops a lot of mcguffins and hints along the way.
Yeah she can flip a whole dragon with her human body, but she can't lift a human with her slime tentacle.
Which is fine, the author is quietly telling us the strength thing only works in combination. It also probably means she can't coordinate using a slime part alone while strengthening the human part with slime. Or at least she's not used to it. This author doesn't really outright tell us a lot of things, that's reserved for humor, but drops a lot of mcguffins and hints along the way.