If the DM wants an actual specific reason why that is wrong.
Tell him to look up Dwarven Plate - Its magical property is "While wearing this armor, you gain a +2 bonus to AC. In addition, if an effect moves you against your will along the ground, you can use your reaction to reduce the distance you are moved by up to 10 feet."
Hes basically given the magical effect of Dwarven Plate to every NPC, except it doesn't require the reaction.
On the subject though. I would just swap Repelling blast for devil's sight/fiendish vigor/mask of many faces/armor of shadows/beguiling influence.
Eldritch blast+agonizing blast is a very powerful cantrip to supplement the bard control and buffing spells.
Tell him to look up Dwarven Plate - Its magical property is "While wearing this armor, you gain a +2 bonus to AC. In addition, if an effect moves you against your will along the ground, you can use your reaction to reduce the distance you are moved by up to 10 feet."
Hes basically given the magical effect of Dwarven Plate to every NPC, except it doesn't require the reaction.
On the subject though. I would just swap Repelling blast for devil's sight/fiendish vigor/mask of many faces/armor of shadows/beguiling influence.
Eldritch blast+agonizing blast is a very powerful cantrip to supplement the bard control and buffing spells.