[Problem with berserker]

i am having problems with my berserker class

i am lvl 3 and no matter what weapon i use or even when i am gordon freeman i only ever heal 4 health each time i hit

i have also asked other people who said they healed 4 health when they are lvl 0

i dont know if its supposed to be like that because ive seen other berserkers last for longer who are lower levels than me

help?