Distant Counter would be great with Quick Riposte... barring that, if you just want to bait with her, then the Wary Fighter would be a good idea and the pair with WoM Reinhardt could be cool although as a mounted mage he will likely not be using WoM so much and it could maybe be better used on someone else. If you pair her with a melee unit with WoM, Sheena can bait a mage, drop below 50, and then your melee unit can come in, especially since melee units have lower range and so appreciate WoM a lot more than Reinhardt would. If you had something warp-healing Linde possible to make though, that could be a great partner as she will swoop in, kill and heal Sheena back to Wary Fighter range.
Another cool idea though it probably wouldn't be totally efficient: Sheena, with her killer axe, -Spd and Quick Riposte would be able to actually make relatively good use of a 5 charge special like Aether or one of the AoE ones. If she gets attacked by a melee enemy that can double her and not die on her first counterattack (so most axe or lance users), 4 actions will be used in that one round of combat, getting the 5 action special to go off on Sheena's first attack at the beginning of your next turn. Obviously this build would be best with Distant Counter so it could work against mages too, but something like Triangle Adept (to keep you in QR range after fighting blues) or stat-boosting abilities will work as well.