Board Thread:False Info and Speculative Discussion/@comment-26399556-20160310193246/@comment-11533671-20160311001323

Stiles has Scott, who we've all seen is able to heal others even if none of the other pack members could.

As for Deucalion,my take is:

1) He's been weakened by that needle thing in his arm for awhile.

2) He was electrocuted by Theo.

3) Hunters often use wolfsbane and other similar weaponry.

The first two would weaken him regardless if they used any supernaturally specific weapon. Even disregarding that, the wound seemed to hit in a normally vital area so I'd imagine it would take a little longer to recover & heal.