4. Sorroblade costs 950 gold more, Tension Bow is 2150 gold, Sorrowblade is 3100 gold (at least in 1.1.7), the price of 2300 gold for Tension Bow has been wrong for ages.

You are correct, I was operating under wrong assumptions. It's now been confirmed that Tension Bow is actually +180 Weaspon Power on the proc, not 180 damage. This +180 Weapon power on top of that cannot crit. And is mitigated by armor.

Wrong information. 50 Crystal Power in 1.1.7.

You may actually be wrong in your thesis there. What I believe you do not take into consideration is that TB's passive is true damage, not diminished by armor. Therefore it provides a minimum of 30 dps, possibly higher, dependent on the length of engagement. The damage of Sorrowblade gets diminished by armor. If we take Koshka as example with her 64 armor, Sorrowblade damage output translates into (150/1.64) 91.46 hp/hit. Of course it's difficult to establish dps here with other factors...