Actually the TV Tropes page that seems more relevant is Sword Plant
The examples you've used all suggest the sword being planted into the ground by the person depicted. I think "planted sword" or "grounded sword" could work.
implications, I'd imagine that planted sword will be the most common, but I can see things like rifles or non-swords falling under a more general tag because of their relative rarity.
Planet weapon would be a good blanket tag. If another weapon type appears to be common enough it could get its own tag, but this should be enough for now.
It's not visibly sticking into the ground, nor the character posed in a way that implies that it is (e.g. a character resting on the pommel with the tip of the blade off the bottom edge of the image).
The wiki for the tag should require the above for use, IMO.
LATER EDIT: I meant for it to be one or the other of the above.
Yeah, hrm... There's a LOT of examples there in which a sword looks like it should be planted, but isn't. (Thanks to hard floors, etc.)
I'd like to revise that last comment to requiring the blade to be visibly impaled into the ground. (And forgetting about images that just imply it, then.)
Edit: Ninja'ed. Oh, even worse confusion from that earlier post. I had meant for that to be an OR, not an AND.
BCI_Temp said: I'd like to revise that last comment to requiring the blade to be visibly impaled into the ground. (And forgetting about images that just imply it, then.)
+1 for that.
Currently all the (few) images tagged planted sword have the blade visibly impaling the ground.