Weapon crafting

[Capstorm]

One of my players want to attach there shield to there halberd “just like the image of the fighter in the players hand book” Should I allow this and if so, should I make them have proficiency in anything.

 

[warpshadow]

If you are using 5e rules I would allow it but say that doing so gives your halberd strikes disadvantage.

 

[The Crimson Binome]

One of my players want to attach there shield to there halberd “just like the image of the fighter in the players hand book” Should I allow this and if so, should I make them have proficiency in anything.

The image shows a spear, not a halberd. I feel like the design wouldn't work as well with a halberd, because of how it's used.

For a spear, I would say that someone could combine the spear and shield into a single object, and they could use it as either one or the other but not both at the same time. The guy in the picture is using a sword in the other hand, so he's probably using that fancy spear-shield as just a regular shield; but if he wanted to drop the sword, I could imagine him switching to use the spear in both hands, although I don't think he could benefit from the shield when using it as a spear.

The real issue is that equipping or removing a shield requires your entire action, so going back and forth would never happen in the middle of a fight. Of course, the major benefit is that it's easier to carry everything, since strapping a full-size spear to your back would be impractical.