As regards Utsuho, there's a couple things I'd like to bring up. The first is a simple matter of units. Namely, you seem to be using kg of destroyed shit as your main unit. This is notably not equal to kg of TNT. One kg of TNT can certainly destroy a lot more than one kg of material.
I've been thinking about this again recently, and it's a reasonable point; kilograms probably aren't the best measure; in fact, the best measure of power is probably...Power (kg * m^2 / s^3).
This has a few advantages; for one thing, looking through the topic, a lot of the numbers that have come up have been in Joules--power is just Joules per second. For another thing, it puts some control on attacks that happen outside of battle; if, for instance Remillia's red mist was released over a period of a week, then you're not getting all of that mist concentrated into one absurd attack.
Of course, the downside of power is that it's not intuitive, so I suppose I should build some intuition:
PUTTING POWER (Watts) INTO PERSPECTIVEhttp://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#Between_1_and_1000_WattsHuman: 1,000 (10^3) Watts
Car: 100,000 (10^5) Watts
Lifting of an object can fairly easily be translated into power; let's say a human is able to lift a 100 kg object 1 meter off the ground in 1 second. The potential energy change is:
E = mgh
Where m = 100, g = 9.8 m/s^2. So that's 980 Joules, and since it was done in one second, 980 J/s = 980 W.
APPLYING POWER TO TOUHOU CHARACTERSThis also gives us a much simpler measure of Utusho--she seems to be much more like a controlled nuclear reaction than a nuclear bomb, and the average nuclear power plant has a power output of...
10^9 Watts
(Unfortunately that's nuclear Fission power plants, IIRC successful Nuclear Fusion power plants have not been demonstrated). Granted, maybe I should be looking at this from a miniature-sun perspective. Power output of the sun is 4x10^26 W. A 5-meter sun has 10^-8 the radius of the regular sun, so assuming it spits out the same energy per surface area that's...
10^10 Watts.
...And looking at Master Spark, we had about 8x10^6 kg of steel which was going to be melted. A quick google search says that it takes 750,400 Joules to melt 1kg of steel. I'm going to be conservative and say that it takes the full 5 seconds to melt the steel. So we're looking at....
1.2 x 10^12 Watts
...Granted, I'm not sure how this carries over to defence. After all, a knife might only weigh 1 kg, so stopping/starting it doesn't take much energy. Might have to think in terms of local pressure as far as blades go.