Result complement https://resources.allsetlearning.com/chinese/grammar/Result_complement
There are endless examples of these 'attempt' or 'procedure' verbs in Chinese which don't include an outcome. The majority of Chinese verbs are like this, in fact. Some examples:
看 means 'to look' but doesn't include the result 'to see'.
听 means 'to listen' but doesn't include 'to hear'.
写 is similar to the English verb 'to write', in that it doesn't specify what the result of writing was (e.g. whether it was correct or not).
记 describes an attempt to remember, without specifying if the information was forgotten or successfully remembered.
杀 means something like 'to try and kill', whatever the result is.
All of these verbs need a result complement to describe a complete action with its result.
For the same reason:
- 带 means 'to carry/ to bring' but doesn't include which direction. Like the examples above. the verb 带 (carry/ bring) needs a result complement to describe a complete action with its result.
带回 = bring back
带走 = carry away
上 in 带上 implies 附上/ 加上 (along with / additionally)
(because)it is dangerous to go alone, (therefore) carry this.
(because)it is dangerous to go alone, (therefore) carry this [along]
A clearer Example:
这条路线很危险, 不带上几个保镖不行 (this route is dangerous, You must bring a few bodyguards along with you)
if you just wrote '带几个保镖' 带 could mean 'guide', 'lead', or 'carry'
一个人去很危险，带[着]这个吧 (because)it is dangerous to go alone, (therefore) carrying this (with you).