You could go 2/10 Hexblade/Sword Bard and get CHA based attacks, two invocations for Eldritch blast, 2 attacks and the sword bard abilities, two magical secrets and level five spells.
Another option is go 2/10 Great Old One Warlock/Lore Bard. This gets four magic secrets, two invocations for Eldritch blast, the Lore bard abilities and level five spells.
10 Bard/ 2 another is gold for me. With 10 Bard/ 2 Warlock I would take above all Devils Sight. Wether you then take the Eldritch Blast damage boost or the push back alternative from Repelling Blast depends on your plans about the use of that cantrip.
