Bound Shadow Blade

You intensive and frequent training and your use of the Shadow Blade made you exceptionally adept and it’s summoning and use.

When you are using a Shadow Blade, you can hold concentration on a second spell, as long as their combined level is equal to or less than half your spellcasting class level.

The maximum combined level might be adjusted by your DM on his own discretion. Other Variants include but are not limited to:
- a combined level equal to or less than your highest spell slot
- a combined level equal to or less than your spellcasting ability modifier + your proficiency bonus