What duration can an effect that moves materials have, when generated with the Philosophical Controlling of an elementalist (Hedge Magic p.25)?
Nowhere do I see that it lasts only one round, only that it takes a round to cast. In fact, when used to increase Soak it uses Concentration as a duration.
So could the elementalist levitate an object (or person) and keep it afloat as long as he concentrates, for example? Fight with a sword for multiple rounds? Use a wind to keep attackers away or fill his boat's sails? All of this seems reasonable to me.
Would that only cost a single Fatigue level, when the effect is initially cast? Again, I think only a single Fatigue being spent seems logical.
The tricky part is whether one could extend the duration of an effect for longer without maintaining concentration. Perhaps by spending some of the Controlling Total to purchase magnitudes for an increased duration? (Probably not)
The examples given in the text are Concentration (for using control over materials for soak), or "as per theurgical Controlling" for commanding animals (ie a single command).
Therefore I would rule it lasts Concentration duration for anything non-sentient, or a single command for animals. No, I don't think you can extend it beyond duration - that's why other traditions are more versatile, and why Hermetic Vim magic gives Hermetic magi an extra edge over the hedge traditions.
I think Concentration duration could also be used for living targets, provided the effect is purely physical, not mental. For example, the elementalist could levitate a living creature (including himself) as long as he concentrates.
What he could not do is control the behaviour over time by concentrating -- that falls under the the "single command" category.
Can elementalists do that,? Interesting
I think they should be able to, at least for Philosophical Controlling (Hedge Magic p.25):
An elemental philosopher can affect the motion of natural materials with the appropriate element, or organic materials using his lowest Form as a requisite.
Living creatures are certainly composed of "organic material". But this may be a saga-specific decision. Some may prefer to restrict it to non-living materials (so non-living wood, leather, bone), others may allow living wood but not living animals or humans, etc.
It is a continuum. As a player who is about to play an elementalist philosopher, I am off course proposing that they should be able to.
As humans are composed of all four elements with no specific bias to one, trying to affect your own body's motion through Controlling would use the lowest of your four elements (unless you have the Philosophical/Medicinal/Theurgy major Virtue that allows you to use your highest art). Using strong winds (like an equivalent of Wings of the Soaring Wind) to use Air or sitting on a stone throne to use Earth would probably be easier.
Yes, you have to use your weakest element as a requisite (I quote that part as well).
"Easier" is wholly depends on what your strongest element is, and your score in the weakest, as well as the intended effect.
Hard to levitate using Elemental Fire. Can be complicated with Elemental Water, unless you have something you can float upon. Wind can lack finesse of movement and move things other than you as a side effect. Standing on a rock that you are levitating would certainly call for a Concentration roll, with potentially catasprophic results if you fail or botch.
Also, if you use that effect as a combat spell (Lifting the Dangling Puppet), lifting the target directly may be easiest.