Looking more individually at talents, and having way too much time on my hands in my post exam period, Midnight Sun looks very weak when compared to the deep spell damage reducing talents in Prot/Prot/Feral. Improved Defensive stance, for example, is 6% to all magic damage for 3 talent points, Spell Warding is 4%/2 points and the new (admitedly higher tier) druid talent is 3 points for 10% armor/10% spell reduction.
While I understand that there will be some differences, I don't see why it can't be made all schools. It could be that the DK is deemed adept enough at combating spell damage and it is simply filler, I don't know, but I would guess at significant amounts of the spell damage in WotlK being Frost and Shadow, and if that is the case why not just make it all schools? Or perhaps it is due to pvp considerations.
Other than that, the problems I have are more with the tree layouts than the talents, going deep frost seemingly forcing you not to take some of the better tanking talents, for example, but I expect them to change before release so it's perhaps not worth considering in too much detail right now.
Frozen Runeblade did get me thinking though, and I even had a look at it.
Couple of things I have noted.
Currently, it appears as though it should be ranked. In fact, the only rank of Frozen Runeblade (rank 1) available in the spell data calls upon (not sure if that is the correct terminology to be using) the proc spell of rank 1 flametongue weapon. Again, I'm not sure if I've explained this as well as I could, but in effect Frozen Runeblade rank 1 is Flametongue rank 1.
Frozen Runeblade rank 1 -
http://urlshort.com/wotlk/site/views...?spellid=49142
Flametongue rank 1 -
http://urlshort.com/wotlk/site/views...p?spellid=8024
And the 8026 spell in question -
http://urlshort.com/wotlk/site/views...p?spellid=8026
From this I would say it is safe to assume Frozen Runeblade is unfinished in it's current alpha form. It either will become ranked and be Flametongue for DKs, as in an identicle spell, or something else. Until the spell is finished then speculation on it's use is somewhat limited. I would question the logic of having it scale with spell damage though, I would honestly like to see all DK abilities scale with AP, and the Impurity talent done away with.
But anyway! The reason I decided to look into it was simple, I wanted to see if there was any chance of it being an alternative to Windfury. Obviously Flametongue isn't competitive with Shaman windfury weapon, but the totem only works on white attacks, so it might not be quite so clear, especially if (as I believe is correct?) regular melee attacks don't generate Runic Power.
A few things aren't known at the moment, how much extra damage Frost Strike will cause with Frozen Runeblade for example, although if you were fitting it into a DPS build you probably won't have that anyway. It's worth noting anyway.
Reason I wanted to look at was thinking about an extra melee and the problem of needing an Enhancement shaman. Not that Unleashed Rage and SoE totem aren't huge anyway, but it was simply to consider if a DK would suffer as badly as, for example, a ret pally or a dps warrior without a shaman.
Anyway. Using Cat's Edge and stealing the rotation from above, and the forumlae too for that matter, basically, because I'm only looking for a "rough" idea, as I really don't expect it to be better than WF, or even competitive, I just want to see if it could close the gap somewhat.
Using 70 seconds, so 7 cycles and 20 (well, 21) unhasted auto attacks, we would expect to see 4 Windfury procs. Maths is not my strongest point, but with 445 extra AP (31ish extra dps?) you'd hit for 1162 on average non-crit, x1.3 for crits and the average WF attack is 1510. Now, I assume mulitply this (and this seems to be missing on your calculations Lurker, I am unsure if it is or I am overlooking something? If I've missed it my maths is even more broken than it probably already is!) 1.45 for Blood Pressence, Blood Gorged and Bloody Vengence.
So, 1510x1.45 = 2190
2190x4 = 8760 extra damage over 70 seconds, or 125 dps.
A note here, I'm assuming it would just be a 1.45 multiplier, but could it be 1.15x1.15x1.15? It doesn't make a huge amount of difference, with the latter method resulting in 131 dps rather than 125.
My maths could be screwy, and the other glaring problem is that WF scales, so in a melee group with Battle Shout, Unleashed Rage, SoE totem and elixers/food/flasks/scrolls and so on, WF will obviously do much more damage. Even with any damage reduction through armor 125 dps is clearly an under estimate, but still.
Frozen Runeblade would, assuming no misses/dodges (which seems fair as I have done the same for WF), hit 20 times from regular melee attacks in the 70 seconds. Each 10 second cycle contains 5 melee strikes, adding a further 35 attacks.
So, in ideal circumstances with the above rotation, you would hit 55 times with Frozen runeblade effect. As this is ideal, I will forget about 16% full resists, and various partial resists, but they would have to be considered.
Anyway, in order to reach the (unrealistically low) WF damage of 8760, each proc would need to do 160 damage on average.
The current max rank of Flametongue would do 122 damage per attack with 0 spell damage, and if Frozen Runeblade were to do the same then it would contribute 96ish dps. This would seemingly get a 1.15 multiplier from Blood Pressence, meaning 140 damage per attack.
Couple of things I haven't added here, is that Frozen Runeblade would be affected by CoElements, Misery and possibly Winter's Chill (frost mages might not be popular at the bleeding edge, but they're still fairly common even in PvE), as well as a number of Frost talents depending on build. I only feel comfortable including Black Ice, however, as if we're stripping away all external buffs from WF it is only fair we do the same for Frozen Runeblade.
So, 147 per attack then, still 13 less than (the low estimate of) WF.
At this point it looks as though the two are close, but obviously that isn't actually true. WF not only scales much faster from external sources (AP buffs) but also with the DKs own abilities. This scaling changes if you spec deep frost, however, with Frozen Runeblade gaining from Tundra Stalker and Frost Strike, and WF will actually scale less quickly through talents than Frozen runeblade. If it scales with Spell damage, then deep Unholy will cause it to scale even faster, due to Impurity and Rage of Rivendare. Theoretically, Frozen Runeblade could scale 15% through Blood Pressence + 10% through Tundra/Rivendare, 5% through Misery, 13% through Malediction CoElements and 5% through Black Ice, along with some extra damage through frost strike.
I will take another look, and probably not bore everyone with pointless speculation that time, when the Frozen Runeblade ability is updated.
At low-mid range gear levels or low levels of buffs (10 men perhaps), though, I would not be entirely suprised to see Frozen Runeblade out perform Windfury. Maybe even at higher gear levels for Frost or Unholy spec. A lot will, of course, depend on it's scaling.
Upon a little reflection, I see no reason why it shouldn't be competitive, or better even. There is a large enough thread on it already, but I see no reason why a melee group should require a enhancement shaman any more than a ret pally, or any other number of individual melee specs.