Is the Black Knight Worth it? (Non-Armored Team)

So both my Zelgius and Black Knight are at 40+3. My Zelgius is +ATK and -Res, he's a phenomenal unit; HOWEVER, I don't have the funds to become a whale for this game.

I've thought about making the BK +10, but is he worth it? He has lower base stats and, unlike Zelgius, lacks IVs. I already have a few +10 red units like Tiki, Eirika, Tharja, Olivia, Lilina, and my Arvis is halfway there.

I know adult Tiki is also very good, but the BK has a DC weapon. I know A!Tiki technically does too, but Breath of Fog is more valuable and scores better in the arena. As would the BK's higher base stats.

I was thinking of making my BK+10 and using this build, what do you guys think?
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A Slot: Steady Stance 4
B Slot: Special Spiral 3 / Wrath/ Vengeful Fighter
C Slot: Even Speed Wave 3 / Even or Odd Attack Wave 3
Special: Obviously Black Luna
SS: Quick Riposte (Unless I have vengeful fighter then probably heavy blade)
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Also his level 40+10 stats are

HP ATK SPD DEF RES
52 54 38 39 22
57 56 40 41 24
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If I did +10 him then I would probably dump Eirika for him, which would provide an extra +2 in all of his stats except HP, which would be an extra +5. Additionally SS4 adds another +8 to his defense.