Recently, VesperArcade released a video that outlined some tips for playing Seth. Needless to say, there are quite a few advanced tricks that could be useful for anyone's toolkit.
Opponents will obviously have less time to react against Seth's Annihilate Sword if you're able to initiate this sequence consistently. In addition to this, Seth will also have more advantage on hit and block as he'll require less time before landing on the ground.
VesperArcade also recommends ending juggles with Seth's forward and heavy punch. It's particularly good to do this instead of ending combos with Seth's Annihilate Sword.
While the amount of damage and stun accrued will generally be about the same, Seth will be able to achieve better corner carry and Okizeme using this attack.
For the rest of the tips, check out the video below: