DarkNightwing47 wrote:From what I understand of the lore, all Dark Angels in positions of command within the regular companies are all previous members of the Deathwing.
No; induction into Deathwing is only one of the prerequisites for entering the Inner Circle. Ravenwing members can also be inducted into the Inner Circle without having to be inducted into Deathwing - i.e. Sammael, who was never a Deathwing. The Librarius and the Reclusiam also does not require previous induction into Deathwing & to wear
TDA.
DarkNightwing47 wrote:I have come across no examples in lore of the terminator armour being used by anyone other than the 1st company, the Deathwing.
Not exactly quite right - Deathwing go into battle exclusively in
TDAs (apart from dreads of course). It isn't that only Deathwing can wear
TDAs, but Deathwing only wear
TDAs. If you're a Deathwing that is not encased in a dreadnought, you MUST go into battle in a
TDA as it is an honor to do so. If you're Inner Circle and not a part of Deathwing, you can choose to wear a
TDA.