Guardian or sanctury?

Which helps reduce fractional damage taken .. guardian or sanctury?

 

both and neither.

Sanctuary applies 90% damage reduction on any attack with a final damage less than 10% of your maxHP.

Guardian increases your guard recharge based on the number of connected party members.

multi-hit fractional attacks (like spikes) that deal less than 10% damage (armor refinement reduces fractional damage as well) can be migitated to single digits with Sanctuary.
strong single-hit fractional attacks that take away half your hp (or more) should be guarded. Guardian helps to refill your guard power afterwards.

Perfect Defense negates all damage.

 

Nice explanation .Thank you Red_Fox