I always imagined Kitana's Kiss of Death as a special technique she developed or learned that involved harnessing her chi or energy, not unlike Liu Kang's ability to shoot fireballs or Johnny Cage's Shadow Kick, etc.

And as a technique, I suspect she would be capable of controlling when she wants it to work and when she doesn't want it to work.
Furthermore, I always imagined most of the other characters' so-called "powers" were also the result of training.

I always thought those extra powers were to just add a kick to the series. Like how Kabal takes off his gas mask thingy, and scares the soul out of the opponent in MK:T.

I thought that too for a while, but then I started getting more focused about certain things in people's abilities on this game.

well i guess if you get deep into it you could come up with reasons why everyone is more powerful than they appear but i like to think that it takes the ability to concentrate to do these moves(fatalities) and you can't concentrate in the middle of fighting.

When did Baraka shoot his blades out? his projectile move is not blades its some kind of spark he makes when he rubs his blades together.

maybe if he sees this

</moronic humor>

but in all serious-ness, i leave my belief in his power based on the name, it is officially called a blade spark(according to the games). I've noticed he does his move at a very, very high speed, and figured that the speed could cause him to be able to launch some sort of super hot spark from his blades, like rubbing flint and steel.

Unfortunately, that leaves the question of how, because there are no known Metals that are capable of that. The only answer i have is that his blades are made of an unknown alloy(at least unknown to EarthRealm inhabitants)

EDIT: As for Sub-Zero, It's always possible that his super strength comes with the fact that he's a Cryomancer. After all, we have only known the fact that he is a cryomancer for 3 games, so they still have the chance to flesh him out.

this is why i think we gave MK to little credit when they were put in MK vs DCU sure the super heroes were super strong but look at the MK characters they can uppercut people through the roofs etc. thats pretty damn strong :D
but ya sub-zero's origin is still much of a mystery since im not quite sure but the MK story makes it out that not all the lin keui have ice powers since sub-zero was surprised that frost had the same ability. and in MKA konquest when taven faught the lin keui they never used any ice powers only weapon was that ice wond that sub-zero had in MK 4. so his race could be super strong, i mean his brother faught the 5 elements in MK mythology SZ.

barakas move is actually a spark, as named in his move lists, i assume like everyone else focused with chi makes a more powerful spark, or its just an excuse to give him a projectile move since he has no other ones.

kitana i assume she can control her kiss of death power as well as tanya, though i assume they just gave tonya that move because kitana wasn't in mk4.

and since mileena had that "suck you up and spit out your bones move" im thinkin edenian woman have dangerous mouths XD
probably why they seem to be dominant in their realm. which kitanas MK vs DC ending fit so well they basically became Amazons like wonder womans people.

but ya i assume we dont give the MK characters enough credit on strength and powers compared to other universes like DC