D&D 5E - A hexblade pact of the tome?
Well, you can't take the warlock smite ability, no, but that doesn't really matter, because there's no less than three of the paladin's smite spells on the warlock list. Sure, you'll be doing 1d8 less damage with branding smite, and no knock down, but still doable. Couple with the fact that, for the overwhelming majority of your games, you're going to have two spell slots to do smites with? And that's assuming you don't save anything for something like a Blink spell or Elemental Weapon. Or you don't use the spell Hex.Honestly, the big implication here for going with tome instead of blade is that you will only ever get one attack with your weapon, and that won't stack as well with your Hexblade's Curse, Hex or Bestow Curse. Which may end up feeling like there's not much benefit compared to simply using eldritch blast, by your mileage may vary.
Also, great axes can't be used with Hexblade and get the CHA benefit - you can't use two handed weapons.
EDIT - also, be warned that there's debate over if GFB / BB will let you be a reasonable melee character. Arcane Tricksters and Eldritch Knights (before level 11) get a direct boost in power from those cantrips. Everyone else seems to have issues from actual play. Good luck!
EDIT 2 - note that part of the problem with the original pact blade was also that warlocks lack the HP and AC to really thrive on the front line. You'll need to supplement using your spells, which will also impede your ability to smite, or just multiclass.
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