In the episode "defiant" we first come across new weapon technology "quantum torpedos" I thought this was a little surprising, as you might expect the enterprise to have been equipped with quantum torpedos first, as it was the flagship. In a later episode "the way of the warrior" We first see "ablative armor" I find this even more unusual, as not only is it a brand new technology never seen before, but in the later episode "paradise lost" we learn that starfleet wasn't even aware that the defiant had been equipped with such technology. After googling ablative armor I came up with this site in memory alpha http://en.memory-alpha.org/wiki/Ablative_armor it seems that the borg also have ablative armor. Given the time when the borg attempted to assimilate the federation and a sufficient period of time being elapsed between then and the defiants first usage, coupled with the fact the defiant was built to counter the borg threat, I theorise that ablative armor was a technology taken from the destroyed borg cube and later intergrated into the defiant, the very prototype ship built to counter the borg. However this fact doesn't explain why star fleet wasn't aware of the defiant being equipped with it ? surely a starfleet ship would know about that? And where did quantum torpedos come from? memory alpha just states when it was first used and when it was later equipped in more classes of ships. On an interesting side note while looking into ablative armor, it seems it cannot be used simultaneously with multiphasic shielding . Multiphasic shielding protects against radiationa was invented in 2369 by a ferengi scientist and was first used by the enterprise to evade a rebel borg ship by flying into the sun, however memory alpha claims this technology was invented in 2371 ? a discrepancy ?