The EnGenius ECS2512FP Multi-Gigabit 2.5GbE PoE++ switch has 4 10Gbps SFP+ ports available. If you are not using them for fiber you can still utilize these ports.
For one you can connect a desktop or uplink to another switch at 10Gbps using a inexpensive twinax cable like this one.
Another way you can use your enhanced small form-factor pluggable tranceiver generally called SFP+ ports is with a copper 10Gbase-T Adapter I tested several and found that the Wiitek SFP+ to RJ45 Copper module works well with the ECS2512FP. The switch detects it as a 10Gbps adapter but it will internally reduce rate until it gets a link.
I tested with my laptop and a cable creations 2.5Gbps USB adapter and got link at 2.5Gbps I did throughput testing with iPerf.
Depending on your cabling this adapter will link at different speeds for a 2.5Gbps 2.5GBASE-T connection you can use Cat5e at 100 meters . If you have Cat6 you can do 5Gbps 5GBASE-T or Cat6A will do 10Gbps 10GBASE-T.
In conclusion there are ways to utilize your switches SFP+ ports even if you do not have fiber. Especially with PoE switches you want to reserve the copper ports for powered devices and use SFP+ for uplinks whenever possible.
More information on the EnGenius ECS2512FP Multi-Gigabit 2.5GbE PoE++ switch here