www.cps.gov.uk/legal/s_to_u/sentencing_manual/attempted_murder/
Here's a link about attempted murder, with the conditions for being charged with this, and sentencing information. With that sentence it must have been a Level 3 (lesser) offence, but it would still worry me, OP. Read the information.
Extracts
'General factors, culpability and harm
Attempted murder requires an intention to kill. Accordingly, an offender convicted of this offence will have demonstrated a high level of culpability. Even so, the precise level of culpability will vary in line with the circumstances of the offence and whether the offence was planned or spontaneous. The use of a weapon may influence this assessment.
There are critical differences between murder and attempted murder; not only is the intended result not achieved but also, for attempted murder, there must have been an intention to kill whereas a charge of murder may arise where the intention was to inflict grievous bodily harm.
...
However, although the degree or lack of physical or psychological harm suffered by a victim may generally influence sentence, the statutory definition of harm encompasses not only the harm actually caused by an offence but also any harm that the offence was intended to cause or might foreseeably have caused; since the offence can only be committed where there is an intention to kill, an offence of attempted murder will always involve, in principle, the most serious level of harm.'
For this charge - there must have been a deliberate intention to kill the other person.
I know 20 year olds can be hot headed. I know they can fight. But this intention takes it beyond that.
There's also the concealing it from you. OH had a bit of a lively past, yes got into fights, got locked up overnight a couple of times, got bound over once...when he was younger. He told me all about it a couple of weeks after we met. It did make me think twice about him - he was willing to take that risk to be honest with me. He's grown out of it all now - but he never tried to kill someone, even when he was being pretty wild. That would have had me running.