One of our characters created a centaur Eagle totem barbarian (level 3) - which I thought was a good idea. But to duck and weave in tight spaces, she'd need high AC, so she came up with a character wielding a lance in one hand and a shield in another. Whilst wearing scale-mail, she'd have a total AC of 18.

Problem is, could a centaur be counted as "mounted" to use a lance in one hand and a shield in another?

One of our characters created a centaur Eagle totem barbarian (level 3) - which I thought was a good idea. But to duck and weave in tight spaces, she'd need high AC, so she came up with a character wielding a lance in one hand and a shield in another. Whilst wearing scale-mail, she'd have a total AC of 18. She was using the Guildmasters' Guide to Ravnica rules for the centaur race.

Problem is, could a centaur be counted as "mounted" to use a lance in one hand and a shield in another?