Many rune mages actually do carry their runeswords in hand at all times, usually only even wearing the harness to attach it to their backs when they have to make some kind of official appearance (assuming that they are in a position that requires official appearances to be made; most Rodorian rune mages serve the duchy of Zerul, after all, and as such have duties to uphold) since it is part of the Zerulic rune mage "image", and most others come into the habit of reaching a hand behind themselves to keep the sword steady whenever they're moving around, particularly if they need to run. The only ones that voluntarily keep their runesword on their back are the ones that are either unwilling to question their instructions upon receiving it and the ones who lack the power to keep the [I]Unity[/I]-rune perpetually active... or the ones that just want to preserve their magical energy in anticipation of needing all of it imminently.
The spikes are (under normal circumstances) almost always pointed towards the holding hand, yes, though it should be noted that this particular detail is far from an intentional part of the design of the swords; the crystal hilts "grow" like this on their own when they are created by feeding magical energy into the initial crystal, and just as the handle rarely grows longer than to fit the grip of one hand (one [I]could[/I] just keep growing the crystal to produce a longer handle, of course, but this would also cause the spikes to grow even longer, making them more dangerous (the instances where the handle does manage to grow longer without the spikes becoming a significant hazard are usually reserved for special weapons for special people)), it rarely occurs that it grows very small spikes, and even more rarely that it grows none at all. Crystal hilts where the spikes are deemed too dangerous are actually discarded, broken and recycled rather than attempted used, and even the ones that are acceptable - albeit initially still dangerous - have their tips dulled so that they aren't actually sharp, but at most just in the way. The spikes can't be safely severed, either, or the crystal would lose its proficiency at channelling magical energy.

And yeah, heh, some things are just not meant to be taken seriously; I often find myself facepalming in early stages of games or movies where the actors do things that are clearly in no way actually possible (magic excluded, obviously, since that always follow different rules than the ones we know; things that would have seriously injured or killed a person should still severely injure or kill them, though... or at least that's what I think) until I decide that such is the norm in that particular instance and just stop applying the laws of our world to it altogether. That said, unrealistic as though it may be, I find myself thoroughly enjoying at least several of the Final Fantasy games... Ironically FF7 is by far my favorite, featuring its main protagonist with the infamously huge Buster Sword and its main antagonist (possibly my favorite antagonist of all time, maybe tied with GLaDOS from Portal) with the equally infamously impossibly long Masamune. But yeah, there is a time for realism and a time for craziness, and I think either can be enjoyable.

While I'm writing: Ashgan, are you there? It's been a while since we heard from you, and I'm starting to get worried...