Any chance to see some units reanalysis?

The admins here are only people just like us, so I imagine that it might be difficult to adjust the builds and analyses when any new skill comes out. If you feel that it will be good on Chrom, then give him the seal and try it for yourself. There's nothing preventing you from doing so if you have him and the seal as well.

I personally think that res is still his dump stat and even the extra 7 res + 4 from sealed falchion won't have a big impact. The extra 7 atk from the brazen seal is pretty good tho and it goes well with his exceptional attack stat.

I agree with what Guts said.
Also I don't think you can reevaluate the analisis like that, even with Brazen atk/res his res is still low and he will get 0RKO by any character that hits his res anyway, even before getting into Brazen range. Note that any mage will be able to double him so even green mages will kill him before entering Brazen.
You also need to consider the opportunity cost of running Brazen atk/res instead of any other seal which may give better results