Waaaghpower wrote:The suit is the priority
I'd say this depends on three factors:
- how old the suit is and who wore it before, i.e. if it qualifies as a true relic by itself
- how renowned its current owner exactly is, both in terms of public as well as political influence (which is usually connected, but there are exceptions)
- who actually ordered the rescue mission
Normally, it is the Sisterhood who would be expected to despatch a mission to save their heroine (or recover her remains for proper burial), but it is entirely possible that the Inquisition gets involved as well - either because a Puritan Inquisitor feels it is warranted, because a neutral Inquisitor wants to collect or repay a favour with the Sororitas, or because a Radical Inquisitor would like their hands on that suit of armour. It is entirely possible that both the Inquisition as well as the Sororitas conduct their operation independently from one another (with potential for a violent confrontation if they meet unscheduled), or that the Sisterhood is entirely unaware of the matter and thus left out.
If the lost suit of armour is not itself a relic, the Sororitas (as well as many Puritan Inquisitors) would very likely prioritise its owner, for Imperial heroes are generally held in higher regard than technology by them, and the Sisters would gladly trade a hundred suits of power armour (and their wearers, if need be) for the left thigh bone of some long-deceased saint. This is different to how both the Imperial Guard as well as the Space Marines treat the value of machines - the former because a Guardsman is worth gak, and the latter because they really revere their equipment a lot once it has achieved a certain age.
Of course, if the suit itself was a relic, things are different for the
SoB as well, and studio fluff notes how many Ministorum priests cringe at the Battle Sisters carrying important holy relics into battle time and time again rather than locking them away in some vault to collect dust, so this is also a possible angle.
The above is my opinion based on
GW fluff, but I'd say you have a lot of options for paths to develop your story to.