The short explanation for warlock blade pact is that if you take the improved pact weapon invocation you can use ranged weapons as your pact weapons (and hex weapons if you are a hexblade), which then means you can also use your charisma modifier to attack with it, and you can eldritch smite through it as well. Alongside this, as you play the character you would naturally aesthetic your spell delivery as being done through your pact weapon as well, so even though you aren't technically shooting spells, you can aesthetic that scorching ray as being bow shots, perfectly legitimately, etc.
Mm. And something I love about Tasha's is it codified retheming into the rules. While it would be a tad bit MAD to do, a Celestial Warlock could take pact of the blade and improved pact weapon to take a bow or gun as their pact weapon, and then retheme their healing as if they were shooting their allies with arrows of healing light or something, which I have always had as a funny thought to do. They will never outdo the Paladin or Cleric, but it would be fun to play cause it still would feel effective. Essentially, with a little creativity nearly any concept can be achieved, including ridiculous ones, and often they are still balanced.
