Knockbacks that can be nullified with Arm's Length can interrupt certain casts

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Date & Time: N/A
Frequency: Always with certain knockbacks that can be nullified with Arm's Length(This issue doesn't apply to all of them).
World name: N/A
Character name: N/A
Retainer name: N/A
NPC name: N/A
Monster name: N/A
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Housing: N/A
Steps:
1. Find an enemy with a certain knockback that can be nullified with Arm's Length(For this example we'll use Sephirot's Malkuth knockback which he uses right before Storm of Words add spawning)
2. Use Arm's Length to prevent the knockback while also casting certain actions(For this example we'll use SAM's Midare Setsugekka).
3. The knockback will be nullified but the cast for Midare Setsugekka will be interrupted because there is no "Spells/Weaponskills can be cast without interruption" effect.

Surecast has this effect, but Arm's Length doesn't because melee jobs did not used to have casts except PLD. PLD got a trait which prevents cast interruption upon getting Holy Spirit and now in most cases they are instant casts.

I do remember not being able to do much about it on a Samurai in the past, other than to delay using it and start another combo while the knockback is being cast. Maybe a similar trait would be useful for them.