jgsugden
Legend
I'd say no. They are not equivalent, and it provides a significant upgrade in power to the PC for no cost. You're adding a lot of damage each round, especially as they advance in level. I am pretty open minded about about these types of swaps, but you're asked to make a commitement to the class in order to get this benefit, and they are not making that commitement.
In this circumstance, I would allow them to trade out blade flourish or their fighting style for an invocation, but they'd still need to qualify for it. Otherwise, they'd need to devote the levels to hexblade to get the invocations.
On a side note: When players want to dip for Hexblade in my games, I make sure they understand that they're making a deal when they take a level of Warlock, and that has consequences. The deal isn't always with a sentient weapon from the Shadowfell - but it is something dark and powerful - and the PCs are expected to live up to the terms of the deal. The deal will be negotiated witht he PC (usually on a high level - not detailed) and will impact the campaign. These deals are RPG gold - but you need to make sure the warlock feels like a warlock .... not an eldritch archer with few spells.
In this circumstance, I would allow them to trade out blade flourish or their fighting style for an invocation, but they'd still need to qualify for it. Otherwise, they'd need to devote the levels to hexblade to get the invocations.
On a side note: When players want to dip for Hexblade in my games, I make sure they understand that they're making a deal when they take a level of Warlock, and that has consequences. The deal isn't always with a sentient weapon from the Shadowfell - but it is something dark and powerful - and the PCs are expected to live up to the terms of the deal. The deal will be negotiated witht he PC (usually on a high level - not detailed) and will impact the campaign. These deals are RPG gold - but you need to make sure the warlock feels like a warlock .... not an eldritch archer with few spells.