You are partially right. Difference is cos of different bonus dmg factors like crit dmg pasive, rune, vicious stance. BUT Death whisper, dance if fire, cov, focus death - all these bonuses multiply each other and base blow dmg. Anyway focus death bonus is still conted different than death whisper bonus. Death whisper gives 35% crit dmg but TH gets +/- 25% stronger blows from it, folloeing this logic, while focus death gives 90%, you would expect 65% stronger blows but in fact you get +- 35% bonus...