and all the shard heroes…
HW isn't really a great talent, so you might be better off just throwing it on a dupe for might.
However, based on your list, it would have to be Rev or Mike. Unfortunately, Rev's own stun will cause some overlap issues, and for Mike you technically want heroes hitting his shield.
That said though, my Mike has a 5/5 HW for the lack of a better talent, and it doesn't seem too awful. I do plan on replacing it first chance I get though.
I would put it on Mike. I actually just switched from that to a 5/8 Bladeshell in thinking it would be better (which it would be 8/8). However, there are better talents on heroes to invest the significant amount of fame it takes to bring a talent to 8/8, and with the new update requiring even more fame (augmenting), I don't know if I will ever bring Mike up to 8/8 and therefore 5/5 HW would have been better for me. Mike is one of the few heroes that doesn't really need a great talent. By the time you are able to make him 8/8, he probably won't be relevant anymore.