I have a 1721 with a 10 baseT wic configured with duplex full paramenter.
When I plug the rj45 wire into the switch, the fdx led does not enable.
10BASE-T is not a full duplex specification.
On some equipment you can set 10 Megabit, full duplex and it'll work.
On some equipment you can set 10 Megabit, full duplex, and it'll reject the parameters (with an error message)
On some equipment you can set 10Megabit, full duplex, and it'll look like it accepted the setting, but it won't work.
In any case, if you set 10 megabit, full duplex, it is not 10BASE-T; 10BASe-T does not include full duplex as part of its specification.