On Tue, 20 May 2014, David Carlisle wrote:

[...]

If you want \mathbf{Var}  to "look OK" then you need to kern the V and a
and that means (as far as I understand the current situation) either using a
text bold font or having tables somewhere in the macro layer and inserting
kerns "by hand",  that is: make the macros iterate over every character
inserting
kerns where needed. (but maybe luatex and or xetex can modify the font
metrics