In version 2.0.5c:

Using a Spellstrike Touch of fatigue as a spell combat action with levels in Archeologist and Sword Saint calculates the Archeologist concentration (the lowest) when casting defensively instead of Sword Saint's concentration (the highest). This is also through both Tof that are given through the different caster classes which should not give the possibility to give an extra attack regardless for the Bard class.

This makes Touch of fatigue and the extra attack from the combination useless and is a major bug.

2lvls in Archeologist
3lvl(and beyond) in Sword Saint