You're pretty quick to criticize. Reaping is not pointless as you do not make use of Blood runes and in between mobs its a good idea to open your options more as to how many scourge strikes you can use, especially when the mobs are tougher/elites. As far as instancing/raiding goes it should be great since your entire damage revolves around unholy/frost and having more of those never hurts now does it? Scent of Blood is honestly just the same as "Dirge". It's not worthless because unlike "Dirge" it can generate off being simply struck in combat which ironically enough would be more frequent in leveling and you get 3 strikes of 5 runic power rather than the occasional 5 runic power from one attack. 5 Runic Power isn't that lovely and both of them are sub-par talents but my method makes you spend less in Blood.
Desecration isn't going to be doing much while you level since you're constantly moving and Unholy Aura shouldn't be your issue since On a Pale Horse makes you mount up faster anyways. Both of those talents are not better it's simply a matter of preference.
How you choose it up to you. Dirge vs Scent of Blood/ On a Pale Horse vs Unholy/ Desecration vs Some extra hit/Talents spent else where.
Bladed Armor looks interesting enough. I can agree with an extra 250 AP judging you'll have around 10k-12k armor in DPS gear.
But they're far from being terrible decisions.
I took a look at Bladed Armor and I came up with this more instance/raid based talent build.
Talent Calculator - World of Warcraft
I'd say take Wandering Plague for early instances and when you start doing more serious raids spend those 3 points from WP into Desecration