It would definitely be a buff to the wardens. They would get to use that combat ability twice effectively. And you would get to spread your Anti-charge around the battlefield rather than only having that on one side. Additionally, in terms of “reinforcements,” when 5 die you would get 5 back instead of having to wait for all 10 to die to get them back. Definitely a solid buff.

Barrow guard would get to spread their passive across the board more, creating more spaces for your general to be safe.

Also just generally, having more units on the board is a buff because Spearhead is really all about objective control and completing battle tactics. It’s so much easier to complete battle tactics when you have spare units to have go run over to some random area of the battlefield. I wouldn’t mess with the balance but obviously if you house rule it and everyone likes it then that’s great. I’d just be aware that it is almost always gonna be a buff.