Teifu is another one of the "weaker" Heroside Story Characters, mainly because his ability Enemy Bonus is really not stable, and depends completely upon how your opponent plays. Add to this he can't use techs, and it's harder to diversify his attacks than other Story Characters.

Items:
Zanba x1
Berill Hands x1
Partisan of Lightning x2
Agito x2
Yasha x1
Inferno Bazooka x1
Mechgun x1
Sword x1
Kasami Bracer x1

Action:
Slash x2
Split Boost x2
Sword Attack x3
Right Heavy Punch x1
Round Slay x1
Snipe x1
Guard x2
Punch Guard x1
Reduction x2
Resist x1

Assist:
Saber Dance x2
Dice+1 x1

Optimally, you want to get both Agitos equipped at the same time. Since the Agito has Enemy Bonus as well, added to Teifu's Enemy Bonus, you can attack for 6AP before using any AP boosters, and Sword Attack will up that to 9... and if you're playing 2 vs 2, your bonus will probably be higher than that. Some of these cards are high level, so it might not be a great idea to play Teifu early on, but with rarer cards, Teifu can be pretty dangerous.