Saizo Sacred Seal Choice

Depends on what you're trying to do. From the picture, it looks like you're mostly going for the classic "AoE chip damage" dagger unit, so of course Savage Blow is the best C skill if that's what you're going for.

Close Defense is arguably better than Defense +3 even though Defense +3 fits for when you're battling against other daggers or bow units, so that's up to you as far as what you're going for.

Most people would tell you Savage Blow or Close Defense, so there's pretty much the two options in a lot of cases.

It doesn’t stack with Smoke Dagger. Smoke dagger Lowers it by 6 points whereas Atk Smoke 3 lowers it by 7. So you get one extra debuff point to their attack. If you also are looking to damage chip them, i’ve attached my Saizo for reference. He’s pretty monstrous in battles as the debuffer/damage chipper.

Nice Saizo, I love him!

I run him with Savage Blow in C and Poison Strike seal. This makes the chip effect hit both the target and foes in two spaces, like the debuffs do. Originally I did this just because my Savage seal was getting used elsewhere (Genny), but I have come to like it. His attack is on the lower side so this helps secure a kill on counter to the target. I also run him with Vantage in B.

I also think Savage blow and close defense are good options. I have his weapon defense refined and appreciate the extra defense.