There's a lot of place for most abilities.
Beginner level. The most flexible and effective level.
Being able to move a large mass is very helpful. You can quickly transport supplies around a base, set up mobile fortifications, or crush enemy tanks.
You can even use it to generate lots of power, by spinning a generator.
You don't want your squishy mages getting within 50 meters of enemy guns generally, so you wouldn't want them crushing infantry generally, but it might be worth it to take out heavy artillery or tanks or trucks.
Bridges, barriers, bases, there's lots of uses of walls for quick fortification. Soldiers who are in a fortification classically take ten times as many troops to defeat, so you can act as a ten times force multiplier so that your soldiers are always covered.
Great for building, great for setting traps for enemies.
Intermediate. The weaker and less flexible level.
Not very useful. RPGS can penetrate rocks, if you're within firing range explosions can wreck you. If you can do it for a long time, could make a good way to carry equipment, on the rock armor.
Useful for insurgents, as you can wreck an area, but chaotic enough that most modern militaries aren't gonna want rocks bouncing around everywhere. If you can move a hill of rock though, that's useful, as you can make very big barriers or move a lot of mass.
You don't want to be close enough to enemies to need to fight with sand. We already have smoke grenades and such, but this serves as a way to cheaply make sand barriers to stop enemy fire.
Amazingly useful, the ability to ambush enemies and move supplies securely is amazingly useful for war.
Master level. The most useless level.
You don't want to be close enough to guns to use this offensively. We don't really need lava in modern warfare, though you could use it to make traps cheaper but more visible, e.g. rather than having a sinkhole with an IED in it, have lava in it.
Useful if you need to do area denial.
Useful in the past when glass was hard to make, now we have lots of it. Could be used to make prettier buildings.
You could use it to carry lots of stuff, by manipulating glass.
Could be used for repairs, but we already have lots of technology that can do metal manipulation.
You could use it to carry lots of stuff, by manipulating metal.