Applejack use his strength, but Rarity use his magic.

@Prof.NightJack  
Wouldn’t that be more dangerous?

@Background Pony Number 17  
>Rarity’s signature spell, she can sense gemstones buried in the earth. That talent alone would make her the richest Unicorn in Equestria.
 
Yes, gem finding is her special talent after all so she is really good at it. I don’t know what makes you think it would make her rich though, since it’s pretty well established that gemstones are not that valuable in Equestria. Sure their value seems to change every now and then but this show is known not to be so consistent anyway. We’ve seen that it’s more profitable to grow apple trees on a land filled with gems. Everyone seems to have gems and will give them away for Spike to eat for such a task as taking care of their pets.
 
Besides, Rarity uses gems mostly to decorate her dresses. And as a element of generosity, surely she would have offered to find some gems to pay for the city hall repairs when it was needed if gems would have had that much value but they don’t. Rarity earns money by selling dresses. Sometimes with gems and sometimes without.

@Background Pony #A856  
Rarity is more a powerful magic user than she lets on. She’s obviously not god-tier powerful as Twilight Sparkle, but she’s got a fair number of tricks and is pretty damn good at them:  
– Levitation. All unicorns seem to know this one, but Rarity carries it to a whole new level. She can lift and move large, heavy objects, and handle multiple objects simultaneously and with fine precision.  
– Mending. As seen in Look Before You Sleep and Rarity Takes Manehattan, she can fix broken objects to make them good as new. Maybe not that powerful a spell, but incredibly useful in a wide range of situations.  
– “Prettifying”. Rarity knows some basic transformation magic that can take ordinary objects and turn them into more beautiful versions of themselves (stage curtains into a fancy dress in Boast Busters, tree branches into topiary in Look Before You Sleep). It has its practical uses, like in the cartoon here.  
– Dowsing. Rarity’s signature spell, she can sense gemstones buried in the earth. That talent alone would make her the richest Unicorn in Equestria.

LOL…!..XDDDDD

@Background Pony #8C27  
I’t said in the show itself that unicorns have only a little magic power. Twilight of course is an exception with magic as her special ability and thus she is OP as fuck.
 
Everything is possible in fanfics. People often really seem to make unicorns really powerful in fics, often putting even Twilight’s skills to shame. In fics, powerful magic is used as a plot device. Yes, it’s pretty cheap but works for writers that lack imagination. Or maybe they don’t like the unicorns the way they are in the show. Hell if I know…

behold! the Unicorn master race!

This kinda raises the question, just how powerful unicorns are? In most fics I read, the unicorns can do some pretty overpowering spells. In the show, they only one powerful spell once and is never brought up again.

What a waste Rarity, you should of turned them into planks.  

I think not even Celestia could do that, but whatever.

This is what the tank feels like in a group of casters.

And then they give chase anyway, and give them splinters.